Great suggestion about PPL and the combination. We are currently looking to buy and have found the PPL data very helpful. They certainly seem to be able to sell lower than anyone else, though! Their numbers tend to come in at lo to below lo Nada base retail. We ourselves are not having any success getting a price like that, however. I would love to know their trick!
Another place to find some sold prices is on RV Registry. There's no way to know for sure if those are the actual sold prices, but that is the intent. I emailed the site and asked that specific question. They said those are the sold prices as they are reported to them. However, I would think that overall it's decent information.
I have been doing a lot of research to try to determine market value to help us in our search. It's not an easy thing to determine. However, I'm coming to the conclusion that getting it below Lo Nada is a good deal and that at Lo Nada still an okay deal but anything out of midrange Nada is probably not so great. (and I'm using base Nada - not the one specific to that particular MH). Would be interested to know what others think of these conclusions. True market value is a challenge to determine.