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

I'm semi retired, but I teach school on one (school) year contracts. Because I am semi retired, I can't collect unemployment during the summer months as per my contracts. (I am service connected retired from the US Army and I took Obama's early retirement from the Post Office)
I sell locks, lock sets, and correct, hard to find keys at Carlisle and Mopar Nats.
I do well enough that it covers my costs, and it usually covers what I make from my teaching salary for the three months I'm down.
I enjoy doing it, it's fun to talk to people, it's cool to be able to help people and guys usually are impressed with my cutter set up.
Carlisle is the best. I can do more in one day at Carlisle than I day all weekend at Nats.
The downside, I never get to see anything at Carlisle unless it drives past me. I'm always waaayyyy to busy to break away to look for stuff.
I do go to the swap meet at Hershey PA. in the fall. That's the ultimate swap meet if you never been. You'll have to sort thru a bunch of stuff, but I have found that can I make money off something from every table.