Jim, NADA only goes back to 1990 so value is subjective. Figure to spend $$ for generator and tires, plus general stuff to make you confident enough to put your family in it. Asking price is a place to start. Buying is a negotiating business. Make them an offer you can live with without insulting them and you'll find out fast if they are ready to sell.,, and what their bottom line is.
Good luck, let us know how you make out. We're all very interested to see what the market will bring.
1984 28' Funeral Coach
Former Rolling Showroom & PuttLab (now party bus)
"I'm not an expert. But I did sleep in an Airstream last night."