It is my opinion that the collected knowledge on this site is more capable than any appraiser at providing a fair market value for a coach.
First, if anyone goes through the P-stuff ads, Coopers, RV trader, plus countless other sites and dealer ads it will reveal prices are all over the place. What is not revealed is how long some of these coaches have been on the market. The Z ship, a late rivet model Liberty had an asking price that was obscene. Yet an appraiser will use prices such as that to conclude a fair market value.
Compare the selling prices. The real selling prices, not what was put down on paper reflecting an inflated trade in price so the deal could be financed. Those represent real market value.