It's a low-end model, what we euphemistically call "entry level". The main design & construction criteria is keeping the price down while still delivering a working rig. That doesn't make it bad, but you need to keep your expectations within bounds.
You didn't mention the size of the Chateau, but $20,000 is probably around average retail pricing. Condition is everything in an older RV, so check it out thoroughly. Especially the tire age (not tread - age!) and batteries - that pair of things can cost a retty penny if they need replacing up front. And of course look carefully for any sign of water leakage anywhere.