Yep, for most people that might seem a sensible way to go, but without wishing to labour the point you can't issue the buyer with an invoice other than for the full selling price, and he can't pay you any less than the full selling price through the Paypal system.
When I bought the Panther earlier on this year I thought the seller had a bloody brass neck asking for a Paypal deposit and the rest via bank transfer/cash (via the bike courier) etc. He sold his bike now pay the fees, and stop trying seeming endless wangles to save thirty quid, all of which benefit the seller not the buyer.