That is a great and impossible question to answer. I searched all the sources you mention above and some local dealers and never felt there was any consistency. I think I over-paid for my truck but compared to all the dealers and web-listings the truck was in great shape for what I considered to be a fair but high price. I guess I was satisfied to over-pay a bit for a truck that ran well, had lots of original components and the body was in good shape, although it has a lot of mud.
I kept digging through all the sites you mentioned and eventually purchased from an owner in Atlanta who I did find from these sites. I trusted him and continue to be satisfied with the price and purchase.
Happy to discuss my price privately if you PM