When i began the search for my Class C I found the models I liked,I went on NADA and other sites and got a ballpark figure of what the coach was worth. I continued my search
for all coaches nationwide similar to the one I was interested and compared prices. After a bit you see they all start to be within a certain price range. Then you look at options,
etc. The coach I wanted was a private sale and in Minnesota, I live in Ca. Off we went. Well worth it.
I did find a document that showed the depreciation percentages per year on RV's but it all depends on condition. A unit well documented as far as service records, repairs etc
for me is worth more than something on a dealer lot that may have been repoed and neglected.
If i remember correctly 30% off list price to the original buyer isn't unheard of, maybe even more, but after that it depreciates at a smaller amount over a
certain number of years.