I bought a used popup from a dealer.....I guess you may pay a bit more, but their techs go over them pretty good. They offered a 30 day warranty period, which I didnt need, but nice that it was there. They also spent some time with me on setup and tear down procedures, which helped as I had never owned one before. I tried to show the guy who bought it off me what to do, but he knew everything.....
The 5th wheel I have now, I bought privately...It was as is, where is....a bit of a fixer upper, but I knew that going in. No warranty on a private sale