There are hundreds (if not more) of market conditions that effect the variable price of a given vehicle in a given location on a given day. NADA is just a starting point, mostly for banks and dealers to determine used vehicle values for the purpose of lending. Any vehicle sells for what the seller can get for it moderated by what the buyer is willing to pay. No more, no less. Think about it. If you were selling a motorhome and somebody wanted to buy it for $10,000 cash, then, before you shook hands (transferred funds and closed the deal) someone else offered you $11,000, what would you do?
IMO, as a buyer, you can use NADA as a starting point in your specific negotiation, but, the rest is up to you. Two identical vehicles could sell for drastically different prices just depending on where they are located on the planet. Get the picture?
Chum lee