Well you find out what his price range is, what he has to tow it with first.
Then find out if he wants a trailer for himself, a couple, or a family with pets.
Then find out what he intends to do with it. Park it in a park, take it boondocking, use it in all seasons.
Then come back and give us that information, and get some help. Millions of people are very happy with their units, but having skills to repair them or an unlimited amount of money and patience to have someone else fix simple things is essential.