Old trick, always works with me. Take cash with you, dont talk price over the phone. Go see the car, test drive it etc etc once you know its a good one and you want it. dont make any Ill let you know, lets make an appointment to get it checked at xyz a few days from now etc etc.
Take out the cash of what you want to pay for it and slam it on the hood. look mate heres the money, serious buyer here with cash in hand lets go now and transfer it and save your self the trouble of showing the car everyother day to tyre kickers.
9 times out of 10 this has worked for me. maybe 1 or 2k up and down from the offer made.
Pressurize the seller into selling it.