Don't pay more than low NADA. There are too many used units out there. Just wait for the right one. Low NADA should be your upper limit.
Dealers will overprice so they can give you a huge discount so you feel good about the sale. Start negotiating below low NADA and set your limit at low NADA. Unless there is some special reason you must have that exact unit, there is no reason to pay more than low NADA.
Low NADA is a fair price - you get a decent (not great) deal and the dealer (if he's a professional) makes a decent profit. It's a fair deal and fair price. Both sides win. Anything over low NADA is not a fair deal.