Look it over real good! Especially for water leaks. Check the roof for signs of damage. Are the tires original or have they been recently replaced?
We bought a 2012 Forest River Georgetown 350TS a year ago. It's on the 24klb chassis and has the 22.5" tires. We paid $64k. It has 40k miles on it, had 1 1/2 year old tires, sumo springs front and rear, hellwig sway bars front and rear and blue ox steering stabilizer. The unit isn't like new and still had he new RV smell. It was exceptionally maintained. So we jumped on it.
If the Winnebago your looking at has new tires and is in the same condition I would try for $65k. If not then I would try for $58k.
Also on an RV of that size you don't want a smaller chassis or 19.5" tires. It's not going to handle very good. Yes 22.5's aren't cheap, but no part of RV'ing is. I actually bypassed many decent MH's with 19.5''s! That's my opinion.
Good luck!