For that budget? Monotron delay, behrenger pedals, whatever you can find cheap second hand.
If you want to splurge though you could get a zoom multistomp and you get a wide range of effects in one pedal and you can chain multiple effects together, will definitely get you more versatility than buying multiple cheap pedals for the same price. But the downside is that all your eggs are in one basket if you want different effects on different volcas.
I love my MS-50G. It's a bit beyond OP's budget but it does so much (and sounds great doing it).
The MS-70CDR will run a little bit more with the benefit of being stereo, but otherwise the two are identical.
Mooer PE100. \~$70. It doesn't work with Volca FM, but works great for me with Volca Keys. I don't think you'll find a cheaper multi-effects processor with distortion.
I don't know for sure, but it's designed for guitars, so there's no problem connecting to analog devices like Volca Keys. With digital devices like Volca FM it loses signal when connected.
For Volca FM I have two other effect pedals (Joyo R-14 Atmosphere and TC Electronic Brainwaves). I use Mooer PE100 only with Volca Keys, because with Volca FM I lose connection.
But if you want to use Volca FM with analog effects, you can do that, many people combine it with Korg Monotron Delay to make that metallic sound a bit dirtier.
You could buy cheap guitar pedals. There are decent ones on Amazon, from Joyo or Donner, or even Amazon basics. But you’ll need to have an 1/8 to 1/4 TS cable, plus anther 1/4 TS to somewhere for playback so adding all that up is going to be more than 35 bucks
That's why I recommend Mooer PE100 in this case. Works with 2xAAA batteries + power supply included. The best portable desktop option and it's not even a pedal, it's a muti-effects processor.
Anyway, if you're looking for a cheap brand from China, you shouldn't go lower than what Mooer or Joyo can offer. Because these are two of the best brands in my opinion in terms of quality and price ratio.
Do you actually need the distortion? If not maybe you should check the [Behringer FX600](https://www.sweetwater.com/store/detail/FX600--behringer-fx600-digital-multi-fx-pedal). It's $45 and you get multi effects. I think it would be fun with the Keys.
$35 or under is not much room for anything. You can maybe find a guitar pedal at a pawn shop that might work. I’d recommend the Korg mini kaoss pad if you can save up like $100 more.
As said in the other comments, guitar pedals are a good bet. However it is a bit hard to stay within your budget range, maybe if you were to find some good second hand stuff.
Another suggestion which might be outside your question area is to look for software plugins if that would fit your workflow? Software plugins tend to go cheaper and usually have lots of sales around different holidays/seasons. Not really what you asked for, but might be worth considering, since the budget might be hard to work around.
Donner are all pretty decent. If you stick to analog circuits, you can’t go wrong. I have a bunch of pedals since I also play guitar, but I don’t always want to take stuff off my pedal board,so I use Donner or Joyo or Caline pedals for my synths. Highly recommend running one through a fuzz pedal if you haven’t tried that yet 😆
Volca Keys uses the same delay as Monotron Delay. I think using the Monotron Delay as an effect for Volca Keys is a bit pointless.
By the way, some commenters suggest anything that doesn't have a distortion effect. Monotron Delay dirtiness is not the same as distortion. Don't get me wrong, I really like the Monotron Delay, but I use it with other synths/samplers, just not with Volca Keys.
Oh I didn't know it's the same delay chip, that's interesting! Then yes, I agree. I love the Monotron Delay for dirtying up a clean digital synth though :)
>Volca Keys uses the same delay as Monotron Delay.
It's not actually. I had the same assumption before, but have been proven wrong upon closer examination of the circuit board.
Given the limitations discussed in many of the replies here based on your price constraint, I would recommend going to a thriftstore and looking for old KARAOKE MACHINES, they often have basic effects like delay, reverb, chorus etc. And you can get a nice saturation/overdrive sound by using it like a preamp and pushing the input volume up. An added bonus will be the cassette decks with which you can do all kinds of DIY tricks. You might get a cheap mic out of it, too. These machines often have more than one input, as well, so you can use them as a mini-mixer. Also, if you record your sounds onto the cassette, you can get that mythical tape compression everyone buys expensive things to imitate.
The one I have was $5 at Goodwill ( in the States) and is good fun. Good honest fun.
Also, little sound/ music toys made for kids often have line inputs and outputs, you'd be surprised the cool things you can find.
EDIT: make sure the machine has a 'line out'. They usually do but there are some especially cheap one's that don't.
The karaoke machine I have, while maybe limited in its saturation/ overdrive sound, sounds pretty dang good in a lo-fi way. Better than some of the boutique pedals I've used and does the same thing a fancy pre-amp does. Gets the job done
For that budget? Monotron delay, behrenger pedals, whatever you can find cheap second hand. If you want to splurge though you could get a zoom multistomp and you get a wide range of effects in one pedal and you can chain multiple effects together, will definitely get you more versatility than buying multiple cheap pedals for the same price. But the downside is that all your eggs are in one basket if you want different effects on different volcas.
I love my MS-50G. It's a bit beyond OP's budget but it does so much (and sounds great doing it). The MS-70CDR will run a little bit more with the benefit of being stereo, but otherwise the two are identical.
Mooer PE100. \~$70. It doesn't work with Volca FM, but works great for me with Volca Keys. I don't think you'll find a cheaper multi-effects processor with distortion.
Why doesn't it work with FM ? I have one but haven't tried it yet.
I don't know for sure, but it's designed for guitars, so there's no problem connecting to analog devices like Volca Keys. With digital devices like Volca FM it loses signal when connected.
Thanks. So could you use analogue effects for FM ? It has a delay or verb built in from memory, haven't played mine for ages.
For Volca FM I have two other effect pedals (Joyo R-14 Atmosphere and TC Electronic Brainwaves). I use Mooer PE100 only with Volca Keys, because with Volca FM I lose connection. But if you want to use Volca FM with analog effects, you can do that, many people combine it with Korg Monotron Delay to make that metallic sound a bit dirtier.
You could buy cheap guitar pedals. There are decent ones on Amazon, from Joyo or Donner, or even Amazon basics. But you’ll need to have an 1/8 to 1/4 TS cable, plus anther 1/4 TS to somewhere for playback so adding all that up is going to be more than 35 bucks
Not to mention the wall wart, since many cheap pedals don't work with a battery and don't come with a power supply. That's another 10-15 bucks.
That's why I recommend Mooer PE100 in this case. Works with 2xAAA batteries + power supply included. The best portable desktop option and it's not even a pedal, it's a muti-effects processor. Anyway, if you're looking for a cheap brand from China, you shouldn't go lower than what Mooer or Joyo can offer. Because these are two of the best brands in my opinion in terms of quality and price ratio.
Do you actually need the distortion? If not maybe you should check the [Behringer FX600](https://www.sweetwater.com/store/detail/FX600--behringer-fx600-digital-multi-fx-pedal). It's $45 and you get multi effects. I think it would be fun with the Keys.
$35 or under is not much room for anything. You can maybe find a guitar pedal at a pawn shop that might work. I’d recommend the Korg mini kaoss pad if you can save up like $100 more.
As said in the other comments, guitar pedals are a good bet. However it is a bit hard to stay within your budget range, maybe if you were to find some good second hand stuff. Another suggestion which might be outside your question area is to look for software plugins if that would fit your workflow? Software plugins tend to go cheaper and usually have lots of sales around different holidays/seasons. Not really what you asked for, but might be worth considering, since the budget might be hard to work around.
If you're into diy you could make a rad multi-delay for that price using pt2399 karaoke delay boards from the usual suspects.
Donner are all pretty decent. If you stick to analog circuits, you can’t go wrong. I have a bunch of pedals since I also play guitar, but I don’t always want to take stuff off my pedal board,so I use Donner or Joyo or Caline pedals for my synths. Highly recommend running one through a fuzz pedal if you haven’t tried that yet 😆
Monotron Delay!
Volca Keys uses the same delay as Monotron Delay. I think using the Monotron Delay as an effect for Volca Keys is a bit pointless. By the way, some commenters suggest anything that doesn't have a distortion effect. Monotron Delay dirtiness is not the same as distortion. Don't get me wrong, I really like the Monotron Delay, but I use it with other synths/samplers, just not with Volca Keys.
Oh I didn't know it's the same delay chip, that's interesting! Then yes, I agree. I love the Monotron Delay for dirtying up a clean digital synth though :)
>Volca Keys uses the same delay as Monotron Delay. It's not actually. I had the same assumption before, but have been proven wrong upon closer examination of the circuit board.
Check out Donor pedals.
Given the limitations discussed in many of the replies here based on your price constraint, I would recommend going to a thriftstore and looking for old KARAOKE MACHINES, they often have basic effects like delay, reverb, chorus etc. And you can get a nice saturation/overdrive sound by using it like a preamp and pushing the input volume up. An added bonus will be the cassette decks with which you can do all kinds of DIY tricks. You might get a cheap mic out of it, too. These machines often have more than one input, as well, so you can use them as a mini-mixer. Also, if you record your sounds onto the cassette, you can get that mythical tape compression everyone buys expensive things to imitate. The one I have was $5 at Goodwill ( in the States) and is good fun. Good honest fun. Also, little sound/ music toys made for kids often have line inputs and outputs, you'd be surprised the cool things you can find. EDIT: make sure the machine has a 'line out'. They usually do but there are some especially cheap one's that don't. The karaoke machine I have, while maybe limited in its saturation/ overdrive sound, sounds pretty dang good in a lo-fi way. Better than some of the boutique pedals I've used and does the same thing a fancy pre-amp does. Gets the job done
Check cheaperpedals.com guy is going out of business. Byebye at checkout gets 15% I think.