www.luckymodel.com is out of Hong Kong and their shipping costs are comparible or cheaper than shipping out of the US. They seem to be exempt from duty as well, something which I've been dinged using Squadron and Great Models.
http://www.spruebrothers.com has some pretty good pricing and I'm planning on buying from them in the future. I've heard that he ships in a manner that slips past the customs agents.
http://www.scalehobbyist.com has recently come to my attention as well.
The problem with those three (and which isn't their fault!) is you will get charged in US dollars and the Canadian peso isn't doing so hot right now.
The problem with the Canadian online stores is their prices aren't any cheaper than the LHS. If you have one, that is!