One of the good things about buying used is the original purchaser gets to take that first big hit of depreciation when he drives it off the lot. If the owner is on top of things he will have had most, if not all, of the problems fixed, so you don't have to. And there are always problems, sometimes especially with new ones.
And since it's been quite a while since you did any RVing, a used camper will keep you from losing so much money if you decide it isn't really what you remembered it to be.