Certainly sellers are levied fees as part of doing business using paypal, but I'd checkout the paypal Ts&Cs. Charging extra to the buyer for using paypal maybe against their rules. If it's an ebay purchase, I'd definitely think that it would be against some sort of ebay/paypal rules.
Having said that, I know that paypal supports the concept of either the payer OR the payee paying the paypal fees.
As a slight aside, it is possible to make fee free transfers (not payments) if you are transferring funds in the same currency to someone else when it is not in consideration (e.g. of a business transaction). I used this once (for inbound transfers) when I was organising a reunion and needed cash up front. I gave the bods the opportunity of using paypal, but requested that they specifically flagged them as a personal transfers so that paypal did not levy fees.