Why can't you consider this in your asking price? Is it so you can seem more "competitive"?
Fvck that, ask for a dollar amount you're okay with CONSIDERING the paypal fee and leave it at that.
Example: you want $15 USD for an item and you say "plus 3% for paypal fees". Well that'd be 45 cents... I'll just leave it at that...
its really laughable both ways.