What is the best/worst you've done when selling at a swap meet?

Not exactly a swap meet, but I made out like a bandit on a 69 Barracuda parts car about 20 years ago. My 69 340 Barracuda had an automatic, but I always wanted a 4-speed. I checked with Brewer's, but it was going to be at least $2500 to buy what I needed. I found a 69 Barracuda FB with a running 340, 4 speed, bucket seats, console and an 8.75 with 3.55 Sure Grip on Ebay. I won the auction for $2700. It cost me about $400 to drive to Chicago, rent a trailer and drive it home. So I'm into it for $3100. I took out all the 4 speed stuff, then I parted the rest of the car out (it was pretty rough). I also sold the automatic and the console out of my car since I would not be needing it. I made about $3500 selling stuff. So I got the four speed conversion for better than free.