I had a 2008 Springdale 266 RLL (26') and got $10,500 for it in trade when I got my new trailer earlier this year. The old one had a leak issue around the door and behind the couch. There was also some damage minor underneath from a tire blowout. We had traveled in it on a 3 month trip, lived in it for 8 months and took numerous weekend trips with it, so it got plenty of use and abuse, but we kept it clean and the dealer even commented that it was one of the most immaculate trailers he'd seen when getting a trade in. I didn't want to sell on the private market due to the leak issues, but got what I thought was a very fair price for the trade.
I say this because my old trailer and your trailer look of similar age and size and I don't think I could've sold mine privately for any more than $12k and that's without disclosing any leak issues. I wouldn't do that to someone, so I was quite happy with $10,500 and I still got a good deal on my new trailer.
