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

Back in the mid teens I had a run of making between about 2500 and 3500 a year for a few years.

The worst ones are where you barely make the entry fee back and then have to see if you paid for your gas there and back.

IIRC the best single show take was about 2K.

The funniest show was a local regular all makes swap.
The previous month I had bought a pair of Magnum 500 wheels for $10 each.
Late in the day and they guy didn't want to pack them up.
Said they were Mopar. They weren't.
Took them back the next month and didn't even get them unloaded.
Guy gave me $50 each.

Same show, I had a bumper jack.
Guy asked how much. I said $20.
He haggled and haggled and berated the item and haggled and wouldn't let up.
Finally I said, give me five bucks and just take it...to get him outa my way.
As soon as the money changed hands-
He starts jumping up and down and yelling "I sure got you, har har har"
"that's for a 67 super sport, I got you real good"

I just didn't have the heart to tell him it was for a 72 skylark.