We've been getting the small to medium-small watermelons they sell at Walmart for the past few weeks. Surprisingly, they've been pretty good and are priced at just under $6. I stopped at one of those roadside truck-bed sellers up near Seminole. Yeah...I just laughed when he said $20. I don't care that it's a little bigger. It's not worth $20.
He probably just picks them up from Walmart and marks them up.