My dad bought cars at auction and resold them. Yes, part of what he did was selling used cars. He took me to auctions so I could drive one home if he bought it. He'd look them over before the auction and he told me, "Set a price in your head and don't go over it." That has been good advice. Set the price you want to pay. And be nice to the seller instead of pointing out all the flaws...they already know what they are. Nice pays...arrrogant doesn't.