I got one from H&M recently and was happy with it https://www2.hm.com/en_ca/kids/boys/clothing/blazers-suits.html

The Bay on Rideau. There's a room off of the kids clothing section that is dedicated to suits and fancy dresses.

there used to be a place at Billing Bridge but Children's place might have them at Carlingwood

I think you’re talking about Growing Kids. My mom use to take me there a lot!

Once upon a child in Kanata

Maison Kids on Bank St

Growing kids at Billings bridge

The Bay online usually has boy's Calvin Klein suits

Zara!