Outside of Amazon.ca, I'm not aware of any Canadian game e-tailer that ships consoles to the U.S. Amazon, however, does not carry Crystal Xbox. I emailed them asking.
Two sites that do carry it are BestBuy.ca and Futureshop.ca. I ordered from the latter (free shipping), and gave them the delivery addy of a Canadian bud who will then send it down to me in the States.
The Canadian Xbox will have no problems running NTSC US games. The only thing I have the slightest doubt about is Xbox Live, but I'm 99% sure that'll work fine too.