Matt beat me to it but generally, I can ship from the states for about 30% less than buying from a Canadian supplier, even after the shipping and duties are included. Most stores have agreements with manufacturers and cannot buy from anybody but official suppliers - thus, Nikon lens caps are $7-8 more than off eBay but if Nikon found out a store was buying caps from anybody but them, they would pull the distribution agreement for all Nikon products. In doing so, any camera or item will not carry warranty from Nikon (all of the major manufacturers have similar agreements). Nikon Canada won't work on a Nikon camera which is not purchased in Canada, even if you are willing to pay 100% of the costs, so being an official store is a big deal. Costco is not an official supplier of almost anyone (in Canada, they are official suppliers of Nikon in the States), which is why any camera, TV or electronic device only has Costco's warranty, not a manufacturers warranty.
So, for film, there is not a lot of market in Canada for film compared to the USA (we are 1/10th the population) and stores would never risk losing official supplier status by going outside of official channels. Just economies of scale. I was looking at a lamp on Amazon and it was $21 in the States, same lamp on Amazon's Canadian site is $67.