You worded that to sound like you are doing the buyer a favor by selling them something when in reality it is the buyer doing you a favor by buying. I think 3%, included in the sellers bottom dollar, is a small price to pay to make sure your buyer is comfortable and to build a solid reputation as a seller who is not fighting over 3% with their "customers." Just include the 3% in your bottom dollar and the problem is solved. When dealing in hundreds to thousands of dollars I think anyone who is willing to gift money to a total stranger has bigger problems to worry about than losing 3%