Looking into a used XJ for wife.

So I have a WJ and looking at a used 2000 XJ for my wife, however what is the average value? The dealer wants $5800, however its a 4DR RWD Sport with 142k, to me this sounds highly over priced. I looked up the value and KBB says its retail is approx $3500. Is there something about the XJs that i dont know about and why dealers think they can jack up the prices? Ive attached the link to the vehicle in question. Any insight would be appreciated.

http://ift.tt/1LLwXud

Looking into a used XJ for wife.