As a seller that does this for a living I pay the fees. I take PayPal because I don't take credit cards. I pay the same 2.9% with PP as I would if I took credit cards. Just a part of doing business. I have some buyers that pay via friends and family and some that add some extra to cover the fees but I never ask this of them.
If a seller wants the buyer to pay the fees that's fine as long as it is disclosed up front and not just expected.
