The customs regulations are ridiculously complicated but at its simplest the issue is where the item was originally manufactured.
If the item was manufactured in a country that is a member of NAFTA (North Atlantic Free Trade Agreement, Canada, Mexico, etc.) the heavy customs duties don't apply. But if it were manufactured somewhere else, shipped to Canada and then brought into the U.S. the duties will be the same as if it were shipped directly from the country of origin to the U.S.
I learned this the hard way when buying a pair of ProAc speakers - English made - from a seller in British Columbia and having to spend an hour and considerable money at the border in order to drive them back into the U.S.
If the item was manufactured in a country that is a member of NAFTA (North Atlantic Free Trade Agreement, Canada, Mexico, etc.) the heavy customs duties don't apply. But if it were manufactured somewhere else, shipped to Canada and then brought into the U.S. the duties will be the same as if it were shipped directly from the country of origin to the U.S.
I learned this the hard way when buying a pair of ProAc speakers - English made - from a seller in British Columbia and having to spend an hour and considerable money at the border in order to drive them back into the U.S.