mhsrv.com has some 2020 Quantum WS31's, well-optioned, for $90K.
I have a 2018 Chateau 31E, which is the same floor plan as the Quantum WS31. Here are some of my lessons learned for your info.
- It took about 18 months to work out all the initial issues. Most were minor, but there were a few significant items that happened during the first year of ownership. Factory quality control is poor.
- I made a number of improvements to mine to make it nicer to drive. I got a good alignment, installed big swaybars and a steering controller, and these made a big difference. I also replaced the stock in-dash stereo, which annoyed the heck out of me. And I added insulation inside the doghouse. I still want to do more sound insulation and upgrade the shocks.
- Based on the 2 points above, I would recommend buying a slightly used one. It should have the major bugs worked out and you avoid the large initial depreciation hit. Mine is nicer now than when it was new. However, a new one has the full warranty, which is worth something, so if you can't find a used for much cheaper then maybe it makes sense to get new.
- The huge full-wall slideout has been finicky. It sometimes takes multiple tries to retract. Early this year a dealer did some kind of adjustment on it, and it was working fine for awhile, but it has recently started doing it again.
- The turning radius is huge, so it is very cumbersome around town. We used to have a 24' class C and it was so much easier to maneuver around town, gas stations, etc.