Huron,
Take what Wandering wrote to heart.
Yes, a new unit will come with a warranty, but the value of the warranty is very dependent on both the dealer and the manufacturer. Please read this site extensively on that matter. Ask friends that have what you are considering. Don't have such a friend? That is what this site is all about....
Buying used has a HUGE price advantage. But, if the unit was not well cared for, free might be too much.
With ANY RV, if you can find any evidence of water leakage, leave it alone. Anything with square corners is "stick and staple" construction and even a "small" rain leak for a "short" period can prove fatal.
Matt