Negotiating with dealers to Nada "average price"?

I gave up trying to deal with used RV dealers over this stuff. Almost all of them were asking ridiculous amounts over NADA, while private party folks generally knew of NADA and priced their rigs accordingly and within limits. The only benefit from buying from them would be you know who to scream at when something breaks. Dealer or PP, it's always AS IS. No reason to pay several thousand dollars more.