Craigslist... when the phone starts to ring you're getting close to the right price :)
Seriously, if you're not in a hurry just do some trial and error to gauge the market. Keep in mind it is a slow time of year so be realistic about how much time it will take. Spin by a dealer if it's convenient to see what they will offer you.... add 20% and list it on CL.
In my experience NADA is not accurate. And it's not really NADA's fault - with RVs there are just too many variables - time of year, local demand, condition, region/location, can't find exact model and/or options.
