not sure about you guys but i have found that usps is the best for customs charges, couple times they havent even charged me any and when they have it wasn't more then 10 bucks. when i did use ups one time they charged me i think it was 40 bucks for something that i only paid 50 for.
it all depends on the item and where it originally is from.
with my engine, cause it was originally from japan, it didnt qualify for NAFTA (north american free trade agreement) but if it is sent as a gift there should be no customs