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

You mean it's not a good idea to "gas monkey" sellers? LOL

I love those people. Same as others have mentioned, I have a price on it and you offer 25-50%. Don't have time for you. Most of my stuff even at the marked price was a really good value.

My last day really running a swap spot I barely sold enough to cover fuel/entry. That was the last time I bought a spot. Best days were solid and paid the rent for a few months!
I could always recognize a what I thought was a fair price, and paid that for a part I needed. If a part I needed, I thought was over priced I made an offer. If the guy got pissed and beligerant, I left his spot never to never return again. I have paid premium for parts that were hard to find I needed bad. We all have no doubt.

Back in the day, I bought at small local swaps, I always had cars to build. I could sell a part for $50, make $10 profit and 2 months later need that same part, then have to make 10 phone calls, drive 2 hours, wade thru the weeds and wasps and copperheads to take it off, and end up paying $75 for it!!!
I tried to haul parts to Nats to help pay for the 12 hour trip from Mo. Last time was about 2004 and the price of gas, the cost of swap space and hotels made it NOT worthwhile at all. It works for the locals there. Locals are only 4 hours away!! and sleep in a tent!!