Most NADA values are off the mark by a lot. Buyers often get the base price only and don't consider all the options that are often included in manufacturers packages but left out of the default base NADA information.
When we were searching for our toy hauler, we often had to ask the seller for all the details like which AC they had 13.5k or 15k btu? How big was the fridge? Which on board generator did they have? 4000 or 5500 onan? Was there onboard fuel? Did they have a happijac bed or just the fold out couches. Was there a microwave or a convection oven. Did they have an auto level system or just stabilizing jacks. So on and so forth, blah, blah, etc...
All of these often made the difference in the nada base price and the real value of the trailer.
Let me give you an example.
My recently purchased ATC trailer shows the low selling price on NADA for just under $32 and average selling price for 39k. I then added all the options I could based on my knowledge of the trailer and the price jumps to $51k low, $61k avg which is about right.
However, NADA doesn't list some of the options I have installed like airline L track. Underbody insulation. Winterized plumbing, AM/FM/Bluetooth/USB radio, 50AMP electrical hookup, 4 separate flood lights (2 side, 2 rear) and so on.
My point is get all the information you possibly can from the seller and add the options as best you can in the NADA guide. Then decide if the price is right or wrong for you.