Hello Mark and welcome to the site. I'm also Based in Ontario, Caledon area. Tandy leather can be a great source for leather although doing a search online for wholesale leather , you'll save loads of money if your thinking of getting back into the trade.
www.brettunsvillage.com is based in Maine USA but very affordable leather and never an issue with customs.
Capitial findings in toronto, north york is amazing as well for dye, a large canister is 13 there but at tandy its 27.
If you contact them pls let them know stephen of Green Man Leather sent you!
I recently sold a house in Peterborough, lived there for many years.
Happy to talk more about leather with you. You have experience making horse reins? I'm looking to to offer services of this nature in my neck of the woods.
Stephen
www.greenmanleather.ca