To follow up on Kirk's post here, I own a 2002 model year gas class A motorhome, so of a similar, but slightly newer vintage to the one in this ad, though mine has many updates and upgrades, plus was a much higher end coach when built than the Damon. I try to keep my coach in ready to go anywhere condition, when things break I fix / replace them, I bought mine in 2016, and since then I have put almost 30,000 miles on it, typically taking at least one thousand mile trip per year, and one circa 3,000 mile trip every other year. In order to keep it in this sort of ready to go condition, I find that I spend on average over $2,000 per year in maintenance and upkeep, doing most repairs myself. In 2021 that was $2,000 worth of new tires (RV tires age out after about 7-8 years, even if they have good tread, 2022 was upgrading to LiFePo4 batteries, 2023 was replacing the roof top air condition, and rear brake calipers, 2024 so far has been new front brake calipers, master cylinder, hydrobooster, exhaust donuts, and new front wheel bearings, though a lot of this is one thing lead to another, ie after replacing the master cylinder the bleeder screw broke off one of the brake calipers, then since it was almost time to repack the bearings while I was half way there on labor I pulled the wheel hub and found metal shavings in the bearing grease....
To answer your question about make model, etc. a lot depends on how you plan to use it, though when looking at older RV's condition is the most important factor, regardless of initial build quality. This is not to say that initial build quality is irrelevant, as it sets an upper boundary on likely condition since some materials age better than others, ie full body paint beats gel coated fiberglass with vinyl stickers, real wood cabinets held together with screws beats particle board held together with staples, ...