x2 Numrich is a good place to deal with.
Also, have a look at their international shipping page...they seem to permit $200 limit to Canada, rather than the usual $100. I'd always kept my orders under $100 until I learned this - but have yet to need to place an order with Numrich, since I learned it.
See h ttp://www.gunpartscorp.com/Foreign.aspx
"Company Policy:
....
Foreign orders with purchased parts value exceeding $100 ($200 for Canada) are not accepted."
Brownells and others, the limit to Canada is $100 and they seem to cite ITAR as the reason (no doubt it is).