I am one who goes a bit against the grain and advises buying new, with one caveat: do a year or more of research first and have a camping background.
Everyone told us to buy used when we were looking, but we were finding that we could get a new unit for only a few grand more than a gently used one, so we bought new. We were former tent campers, so we figured out exactly what we wanted in a TT and have had no regrets.
The small problems we have had were fixed by the dealer under warranty. I just liked having that peace of mind and was willing to pay extra for it.
My wife also didn't like the idea of sleeping on a mattress, sitting on a dinette and sofa, or sitting on a toilet that other people have already used.
