title: Accept credit card/echeck payments
body: <p>I bill customers monthly for a service and would like them to be able to go to my website and pay by credit card or echeck.  I can do an integration with Authorize.net/ach direct/paypal/etc, but if there is something open source or some sample code to start with, it would be much easier.  I basically need the user to enter a name or number so I can identify the payment, and the amount they want to pay. The only thing I have been able to find, however, is shopping cart software that doesn't look like it does what I need. Is there anything I can use for this?  (Free is best)</p>