The NADA price is the average selling price gleaned from DMV reports.
NADA is not the asking price.
New RV's typically have a 30% profit in them. Used RV's, maybe that much or more.
A lot of dealers mark them up substantially over NADA, so they can give you a good deal when they knock 10% off. They're still 20% high.

Typically, private sellers make a common mistake and add up all the items listed on the NADA book when pricing them. You are not supposed to add anything that is not standard equipment on that particular model. Do I think a lot of buyers make the same mistake? Frequently.

I won't pay over NADA retail unless it is significantly better condition than the average and definitely not without a warranty of any kind.
Also, remember that with pups over 10 years old, the most important thing is condition and that will affect what it is worth more than any other item.