I think a major player in RV values is the immense range of personalization of a home built airplane. I am in the market for an RV-4 but would entertain the idea of an -8 (I have virtually given up looking) I have looked at many photos and been extremely disappointed compared to the written advertising. Paint, panel, and engine are the big players outside of the obvious craftsmanship.
Personally if I like everything but the paint I would discount it from the market about 10k. I know that is more than the going rate to put a different paint job on a plane, but it accounts for the pain in the butt factor and the, what problems will be uncovered factor as well.
Same goes for the panel. I have found in -4's that the size and shape of the panel leads to "inventiveness" to get things in there. I can't count on two hands how many times I have looked at photos of an aircraft I thought i was interested in and laughed. If you have to do too much work to get what you want it why not just build?
The engine is kind of the same story. If a person wants a fixed pitch 320 and a plane that has the perfect paint and panel has a c/s 360 would they buy it? It is a completely different animal than what they want.
Just some of my thoughts.
Mark