You could get your own merchant account. If your in the US, talk to Joe at
Joe Montella
888 997-5174
http://www.merchantservicesusa.info
You can then use PayWide to take care of password management, affiliate tracking, fraud scrubbing, rebilling, etc. for 10 cents per transaction.
Let me know if you have any questions or your in another country. If your in another country, I can see about recommending a place for a adult merchant account in that country.
Mark
Toll Free#: 1.877.PAYWIDE