I get my rivets from Capital Findings, though they don't have an online store.
http://www.leatherpages.com/Listing/...eather_Ltd.htm
They're super-nice people but they prefer large wholesale orders.
Check out leather supply places in your area, maybe you won't have to ship it then
Winnepeg is your city right? There's a few denim/outerwear manufacturers in your area, I wouldn't be surprised if there was some local suppliers for findings as well. Good luck!