Maybe. Maybe not. It all depends upon the dealer. Some dealers are not permitted to sell to buyers from out-of-state or out-of-country. I would recommend doing some calling around if you're at all considering buying a vehicle from the United States.
Remember... if you want to do things legally you can't just go buy the vehicle and drive it back across the border into Canada like you own it. You've got 5% GST at minimum and various other fees to pony up @ Canada Customs if you're going to do this. Good luck.