that's a great question man...
perhaps it has something to due with import customs/ duty from importing into canada, and the increased price associated with having bi-lingual pakcaging. That being said, I still don't see how that can account for such a drastic difference.
I guess it all depends on if people are buying them. If people are still buying the toys (because they're used to the inflated prices) it wouldn't make business sense in hasbro's eyes to lower the prices.
But any big ticket items I need I usually try and get from the states b/c you're right, they're soooo much cheaper.