Here's another vote for buying things from the US. Bought from both b&H and adorama, no problems, no duty, and a payment of 6%gst and 8%pst when UPS, FedEx or Canada Post delivers the package (I tried all three just to test). Credit cards usually charge a 2-4% fee for the conversion.
US Canon warranties are good here in Canada - there was a thread about a week ago on this, do a search. Tamron and Sigma will honour the 1 year international warranty, but you lose out on the longer warranties (Sigma has a 8 year one I believe).
I *think* Canon Canada has recently adjusted their prices to account for the higher loonie, but I'm not sure. It seems like you don't get as great a deal any more, buying from the US. Check out the online stores located in Alberta. The Camera Store (linked in an above post) seems to have some good prices, and you can duck the 8% pst.