Yeah, it's a common problem. I'll add some guidelines to the 'recommendation' announcement detailing how to incorporate the likely 'receiving' fees when using the recommended 'purchase' route through PayPal payments for 'goods'. Just 'refund' the first payment in full (i.e. rejecting the transaction), the link to do this is found in the details of the payment entry. Then tell the buyer what the fees were and to add that to the total item+shipping cost, job done when the second payment comes through.