Tell the seller to go jump in the lake!!<G>

It's a cost of doing business, the seller shouldn't be trying to get his bidders to eat it. If he had a store, a restaurant, or some other business, he would more than likely have an agreement with a bank, or other 3rd party, to process his credit card sales. He would be in violation of his agreement by asking his customers to pay the service charge & the bank could terminate the agreement.