Research cars advertised online by VIN with AutoCheck - way more comprehensive than CarFax (that's why many dealers offer it for free - it misses stuff) - - it costs $15 but is worth every penny. Case in point - I was looking for a van a couple years ago and found a dealership in a small town with 9 on the lot. By process of copying and pasting VINS, I determined that 6/9 had accidents reported. Went to dealership, zeroed in on the three good ones, test drove each one, hemmed and hawed, picked over them for a good hour or so. They tried to redirect me to the dinged ones, but I declined, saying I liked these three better. Decided on one and started haggling. Best moment was when the guy went back into his office, checked online, and came out and said that I was demanding the best price on a comparable vehicle within 75 mile radius. "Why do you think I came here?" I asked - "Do you want the sale or not"? "I have this much in my checking account and you can have it or not - your choice." He caved, but then gave me some song and dance about how they take a day to prep a vehicle before the customer takes delivery. BS - do it today - I drove an hour to get there. They did it same day, and I drove home a happy boy. Truth be told, I f'in love buying used cars! We leased our newest one, and while we got an amazing deal - 0 down payment, there was almost no fun in it as there was no negotiating. I once read a book by a guy who bought used cars for people for a living - lots of great tips in there that really worked for me!
I am an occasional buyer of "case leftover" lots, particularly of Bowman products - PM me if you have unsearched base/chrome/refractor/non-numbered insert lots from Bowman cases!