The resellers of Credit Card services, the banks, at the start of a relationship
look for around 4-5% of each sale plus demand a minimum income from the
merchant each month, if this is not in sale income, the merchant has to pay the
difference.(At least in the UK)
In the US there is a service which appears to offer better terms (and can be used
on the Internet)
EMS reseller with different terms and a simpler looking form
An alternative for Internet transactions is First Virtual.