While NADA has a lower value, PW's of this age do generally go for at least $40k in this age range. For instance, if you check rvtrader.com today there is a 2006 Plateau with 176k miles for $40k in California and nothing else in that price range for a Plateau. Many dealers will not part with a PW Diesel for a non-premium price. So, if you're comfortable with the future availability of diesel #2/B5 (avoid Minnesota), at least you should be able to avoid the DEF in that age range. I have a 2012 and have been forced to use B20 at times but without any ill effects so far. What I have done buying used, which I think is a very important thing to do, is to have it inspected by a professional. I would contact NRVIA.com and ask for their best inspector in your area. Have the engine fluid analysis done, too. The package ain't cheap, but it is worth it. After all, you're intending to spend many tens of thousands of dollars!