when i was in canada in june (vancouver end) i found there to be little difference. for stuff like the canon DSLRs the prices in the cheaper shops like LondonDrugs were not much to choose between the prices on 7day shop (maybe more expensive than some retailers like pixmania). its hard to gauge exactly cos it depends on the exact rate the VISA choose to use on your card on a particular day, and take into account whatever taxes you can claim back. you may also wanna buy stuff in alberta cos there is no provincial tax thus its cheaper (you can[t claim PST back, unlike GST). The overall impression i got was the in canada digital SLRs were basically the same prices as you could get at home.
also think about warranties. i dunno what its like for canon and other manufacturers but certainly for nikon their warranties work in sales regions. I.e. a nikon camera bought in europe (i.e. distributed by nikon europe) is valid anywhere in europe (i.e. you can buy a french camera off pixmania and the warranty is good in the UK). However nikon europe won't touch a camera from asia (like the ones people will post you from hong kong on ebay) or the north american markets. I.e. you may save a few quid but check it out cos if you're screwed for a warranty then its hardly worth it, especially given than if you're looking at a DSLR then you may need to have the manufacturer remove shit from the sensor at some time. i know someone who's D70 came straight out of the packaging with shit on the chip.
I have heard that canon's warranties are valid worldwide though but as i say you need to check. also bear in mind that if you bought a camera in canada then claimed the GST back you have to send the original receipt with the claim which they don't return, thus you end up with no receipt i.e. no proof of purchase, which could of course also effect your position regarding claiming warranty services.