I've seen them in person (except the slide). They are cute and perfect for some. Many don't have gas but this one does. Some have ugly plumbing sticking out the side to dump the black tank. The 18K price is about what they go for new up here.
Personally, I would rather people buy the above than a "restored" vintage trailer. At least they will be safe.
Do these have real wood paneling and cabinets or vinyl wood grain covered? I have a fairly new Real-Lite truck camper that has a very similar interior look. The only thing that makes it somewhat cheap looking is the fake wood (other than the rails and stiles of the cabinet doors). Otherwise, very functional, comfortable, and safe.