Simply put, the American side of the border (customs) can create absolute chaos when dealing with anything but foam balls passing in front of them, even then they have been known to hold the said balls or destroy them in the process of determining them safe. It has proven far easier in the past to make purchases on this side of the border to keep sticky fingers and paranoid customs officers away from something that I have paid for. US customs is not known for their ability to let things slide, Canadian customs is known for taxing the crap out of anything entering..