And that's how payment proccessors work. Whether a merchant uses GBuy, Paypal, Verisign, or deals with Visa/MC/Amex/Disover directly, they all charge money. So unless an e-tailer makes you send cash in the mail, (and then you have the "Post office tax") somebody is paying that fee somewhere.
Likewise with advertising. Unless you depend on word-of-mouth and good press, advertising costs money whether it's with Google, the radio, tv, or the newspaper.