As a seller, I have sold many many items on ebay and by other internet means...almost all payments being through Paypal. Paypal fees cover many of my store front costs...my bank, my cash register lease, my book keeper...my lawyer.....security...etc.
My prices include this overhead...I cant fathom any reason to ask the buyer to pay for this service as a extra adder. Its like brick and morter stores asking for a percentage on top of the purchase price. I wouldnt pay this to a "real" store and sure as hell wouldnt to a web store. I suggest you stay away from these hams. Silent protest works!