up until a few years ago, it was better to use the .com (US) site because the prices were much lower and duties were not applied. Nowadays, though, UPS and other shippers seem to be finding ways to apply duty + their handling fees (for looking up to see what duty rate applies) and thus, you pay more- and in some cases alot more.
an example. I recently bought an electronic dog collar from cabelas.com. It was the same collar I bought 3 years ago. back then, no duty, just regular shipping. this month, 7% duty applied and a $65 "handling fee" for UPS looking up the 'appropriate duty rate'...
However, the collar is Made in USA and thus should be duty-free under current NAFTA rules... So, I am appealing it, but I don't think I'll be able to resolve the $65 UPS fee. shaking my head at this one!
anyways, if you can- look at the prices on amazon.ca first. especially if you can get free shipping.