I was told that shipping costs will be an overestimate in some cases, but an underestimate in many others, especially because of rising postal costs. Since shipping to Canada at the same rate as a US order is impossible (it is up to 3X the cost of domestic shipping), they are necessarily categorized under the safer "International Order" option.
I feel bad that this is particularly painful for my Northern neighbors. I would like to make it up to you by bringing some books to Canada when they're done. I know Mr. Christopher Butcher of The Beguiling in Toronto. He has basically told me he'd be up for hosting something like this. Signed books and/or punches to my face can be made available.