I'd love to use paypal for its simplicity, but I need a system that will let me charge $30/month, but then depending on a users usage, let me tack on extra dollars. So my question is, how do I charge people varying amounts of money, automatically, and every month? Is there a system that will let me do this that won't involve storing credit cards myself? Sorry for noobishness. Thanks! Robert
Some payment gateways have a customer vault storage system, where you can charge a customer based on a reference number. This way you never have to store any part of a credit card number, just a reference number to the customer. Authorize.net has this feature for an additional fee as well as some other payment gateways. It does have limitations, but is basically exactly what you are looking to do.