Another thought regarding buying used.... I would stay away from the used rental units like the retired Cruise America fleet. Every rental we encounter and that is a big number, is usually blasting along at 70 to 75+. Bottom line, folks that rent them either don't know any better or don't care and they drive the******out of them.
I strongly suspect that most rental folks aren't all that familiar with RV electrical, plumbing , heating and AC systems all of which are easy to abuse if you don't know what you are doing. I have heard of some seemingly great prices if you can swallow the high to very high mileage but think about how they were used/abused before you plop down your hard earned money.
:C