I did very well at the sale that I had. I sold over $100 worth of coins. Mainly wheat pennies. I was selling them at 10 cents each, 15 for a $1. I also offered them in bulk- a half cup (around 150 pennies) for $5.00 and a full cup (close to 300) for $10.00. I had many sorted by year and mint mark. I also had a container full of unsorted ones. Even had a customer sell me a couple rolls that He had in his car. Got a very nice 1928s wheat from that. Will post pics later for that. Sold all of the new pennies I had gotten from rolls at 10 cents each. Several customers stopped to purchase and got back in contact with a guy I new long ago .
I have never bought coins at a yard sale, but have bought foreign currency from one. (Venezuela and Egypt).