Edit: I looked at the photos of one of the rigs at RVtrader and it looked like it had a full wall slide. I'd find out what slide mechanism is used if you look at one with a full wall slide and research to see if there were problems with it. Some of the full wall slide outs have had problems.
Based on our shopping experience, rigs can look a lot different when you see them in person. So be prepared for that. That's not to say that there are some great buys out there, but it can take some time to find them, and it can be a chore to keep traveling around to look at units that look promising.
As to price, aside from NADA which can be on the high side according to many folks, all you can do is search online to see where the prices are. Right now, on rvtrade.com, there are three units listing with prices listed for two of them at $60-70K:
https://www.rvtrader.com/2008-Winnebago-Voyage-32h/rvs-for-sale?make=Winnebago%7C2307464&model=VOYAGE%7C764852867&trim=32H%7C6879&year=2008%3A2008
But, it's all about condition and service records. If you know the general price range, the condition and service records will lead you to determine what the rig is worth to you.
We started out in late 2017 looking for an older gas rig (2005-2008) with the idea of spending $35K or so. After seeing what was available, and then seeing our 2012 Bay Star, we looked again at our budget and decided to spend more. Our Bay Star was in such great shape, whereas the rigs we had looked at that were older not only looked dated, but were worn and/or needed a lot of renovation. I didn't want to get into doing that kind of work.
2012 Newmar Bay Star 3302
Blue Ox Avail
BrakeBuddy Advantage
2015 Malibu
"Get busy living, or get busy dying."
Andy Dufresne, The Shawshank Redemption