Not sure about the US numbers, but importing a non North American built boat into Canada will cost an additional 9.5% duty. If you're buying new I suppose that's in the initial price.. if you're buying used and crossing the border then you'll get hit with the extra..
Nearly 10% could be what makes your decision, all other things being equal, between a foreign boat and a domestic one.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)