I purchased a beautiful '73 Triumph Bonneville 750 out of Vancouver last February. Between the favorable exchange rate and the 25 year or older rule of not having to meet EPA emissions requirements it was a no brainer. I spent a lot of time online researching, printer out some paperwork, filled out what I could. Made sure I had all the proper paperwork from the seller and headed to the border. Declared what I was doing at the border, they sent me inside to see a customs agent.
The customs agent was great, told me I didn't need a bunch of the forms I had, he tried to figure out how to import it with the least cost for me which was a big surprise. 30 mins later and a small duty check and I was on my way. Later titled and registered in WA State no problem.
Plus the Canadians are super nice. My sister lives in Van so she came along for the ride to "help" me check out the Triumph. Just before we left the sellers house with the bike, his neighbor came over with two dozen roses for his wife (it may have been the Canadian Mother's Day or something). The neighbor also had 2 dozens rose for the stranger (my sister) in the seller's driveway.
So I got a killer deal on a sweet bike and my sister got 2 dozen roses from a complete stranger.
I would emphasize to do your online research on the gov't websites, border agency websites and rely less on web forums.
I've have also considered purchasing a newer adventure type van from Canada, there are a lot of great deals, just do your homework and be prepared to be resourceful if things don't go smoothly right off the bat. If you do your homework you should have no problems. -Eddie