Why are used camper prices so much higher than what NADA says they are worth?
Is NADA an accurate guide or not?

It has always seemed on the low side in my exoerience. It really depends on the popularity of the particular model though..

I've been helping a buddy shop for a travel trailer; the NADA prices we've been looking at are super low compared to the asking prices for rigs we're seeing in the Phoenix, Yuma, Quartzsite area. He's looking to spend roughly $3,000 for a trailer to live in, and we're seeing some in that range, while NADA is suggesting the values are less than $1,000. Of course, comparing similar units on dealer lots--forget it! These guys will highjack you all the way to the bank.