When I brought my boat down from Vancouver, I used :
They are in Anacortes, we cleared in Blaine, but it was irrelevant as the paper was already complete.
They were very efficient and handled all the paperwork as well as the financial transactions smoothly. Back then in 2002, the USD was alot stronger against the CAD(about .60), and by watching the currency market for a couple of weeks, I even saved a bit more by timing the 'date of sale',
The cost to do the paperwork was reasonable. I recommend documenting the boat when you bring it in - just a few $$ extra.