If the warranty is important enough that you feel you need one on even a 1 or 2 year old unit, buy new. The cost of the warranty would cover the price difference in most cases.
The components in a TT are warranted individually, appliances, roof, etc have varying warranties from their individual manufacturers.
If you are handy and take care of most things around your home yourself, and do the basics on your vehicles also, you can do most of the basics on a TT also. For those times you cant, find a local independent repair tech to help you. Contact a couple of the local Campgrounds as well as the yellow pages, and use them.