At that price range (the same one I was in when we bought our new camper), build quality is mostly the same depending on the size you are looking at. Most of the fittings and appliances all come from the same couple manufacturers.
Not a deal breaker though, just look at it in person to make sure you are happy with the fit, finish and floorplan. Then just maintain it.
As everyone said, water is the camper killer, even on more expensive quality units. Keep on top of your seals and seams and you should get plenty of life out of it.