We ship between Canada and Us on a daily bases. You will require a broker to clear the boat, and with a NAFT certificate which you can get from the broker which the sell signs there is not duty, but there is a broker fee. Then you have to pay the states taxes, registration fee. Most large boating areas/cities have marine title companies which can handle the whole thing for you. If you finance they might require you to use there recommended broker and title company, so check with them.
the freight forwarder and broker I use is DHL as they are know world wide and have a office at most boarder crossing.