I may step into it when I say this, so please take this in a good spirit...
My brother and wife (a physician) just moved to the Castlegar area from the states. They've been up there a couple years, actually. They notice the large difference in pricing on almost everything. They travel down here to make almost all their big purchases...cars, chainsaw, Christmas presents, etc. It's legal to do that...they pay your GST and all that upon return and still come out better.
The dollars are about equal again as of today. But prices are higher north of the line. I'm thinking it may have something to do with free enterprise. The US is more fully capitalist; a free-market system. Canada appears to be on a more "socialist" track (easy, there...just my opinion) which, in fact, makes things cost more. You do not have the same downward pressure on prices as in a more free-market system. (Although, our prices are going up, too!)
I could go on and on, but I'm not an economist so it would probably tend towards uninformed opinion. But I think this is part of what you're seeing. Frankly, it's been like this for years and years.
grae