We have bought RV's both new and used. Right now we are shopping for a 5th Wheel, preferably a few years old. However, what I am finding is that there are of course lots and lots of new units on the market, but few used fifth wheels just a few years old. Most used fifth wheels are approx. 2007 or older, and we won't buy one that old.
I believe what I'm seeing is that most folks keep 5th wheels for 7 or 8 years or longer. The market in the year range I am interested in is very thin. And even when I do find one 1 to 3 years old, sometimes I find that I could buy a new one of the same model for the ridiculous prices asked for the "slightly used" ones. I may end up buying new by default.