Ask for confirmation of the final delivered price, and there are no laws demanding you pay ANY added fee's other than taxes and registration. Some will add on thousands for transportation. Dealer prep, documentation and even your pre delivery inspection. All of these are just ways of concealing the real price of your unit.
Taxes and registration should be paid to the state where you will be basing it, not necessary at the state where you buy it.
I would also make your offer contingent upon the unit being road ready at the time of your arrival.