Oh dear. Honestly, this sounds like very bad news. From what you've said, buying a boat should be WAY down on the priority list, after you have taken care of more pressing needs. Your own instincts about not wanting to be part of that duplicity are telling you something.
Speaking from experience - when we were building our house, the builder did build it to the contracted price, but after that, there were things that needed doing, from small stuff like drawer pulls (I bought some cute dolphin pulls from Restoration Hardware) to large things like furniture that all added up.
Won't you have things you'll have to buy, like your appliances and so on, or is all that already in the contractor's price? For us, all of our appliances came out of our own pocket; that's just the way the contract was written.
