Ebay policies prohibit the seller from charging a surcharge for use of a payment method. Except that they can charge exchange fees if you are paying in a currency other than the one the auction was listed in. I also understand the surcharge rule does not apply to Ebay's foreign sites, so if you bid on an auction on one of those te surcharge may be permitted.

I am told, but have not confirmed that paypal policy also prohibits these surcharges.