OK, I've done some more research and I'm still stumped. What I'm looking at is a 2005 Pleasure-Way Lexor TD -- which is exactly what I want. (I didn't know that until I saw it, but now I do.) Comparables are hard to find, as Excel TSs and the occasional Excel TD dominate the PW listings.
Here, from listings in the Oodle.com site, are three examples of PWs recently sold:
2004 PW Excel TS, 19k mi., sold for $39,900; NADA value $31,031.
2003 PW Excel TD, ? mi., sold for $39,995; NADA value $26,230.
2005 PW Excel TS, 27,000 mi., sold for $42,500; NADA value $34,021.
And there are many, many more PWs for sale with the same kind of discrepancy between the NADA value and the asking price. I've checked a few Roadtreks for sale; same thing. So I am still feeling the need of some help to discern what's a fair price. If anyone else cares to jump in, I'd love to hear from you!(I already know the part about the fair price being the one I'm willing to pay; I am trying to avoid being a total idiot in this regard.)