Registration and Sales Tax
One more folloy up. When I was checking this issue I talked to the Tax Revenue Dept. for the state of FL. He stated that Florida laws were changed to allow Florida broker / dealers to be more competitive. They do not have to charge sales tax provided you sign an affidavit stating that you will remove the boat within I believe 10 days. You must show them receipts to this effect (gas bill, dock rental, etc). But you can only be in Fl waters for 30 days per year after that. In a private seller transaction, sales MUST BE PAID, irregardless of your intentions to leave.
You might want to check that state''s tax laws directly. A lot of good information here, but like myself, I wanted to here it straight from the horses mouth. Tax evasion (at least in their eyes) is not a pretty thing. Good Luck.