Don't list in your auction that you accept PayPal at all. When you send the invoice to the winner, mention that you accept PayPal funded by cash, in addition to the alternatives you listed in the auction text. Works for me. One catch for larger sellers is that you can only accept $1000 total cash payments into your Personal PayPal account per month.

Personal PayPal accounts have no transaction charges at all, by the way, buying or selling.