It's hard to make money by quilting, but sports-related quilts might sell well. Like QuiltE said, figure out your costs and labor, then decide whether you can sell the items for the amount you need to make a profit. Remember that you will need to keep records and pay taxes, and that includes paying a hefty social security and medicare tax of more than 15% on your profit. You may also need a business license, and the flea market may charge for your booth. It all adds up, so don't price your items too low or you will wind up with nothing for your work.