[bonestamp2]

Not OP, but I use waveapps.com for subscription billing. It was among the lowest cost option I could find, it works well, and it produces nice invoices that you can white label. Once the customer has entered their CC, you can also process incidental charges as necessary above and beyond their subscription. Most clients don't want to deal with billing either, so this just runs the card on whatever frequency you want and allows you to run the card whenever else you need to. If someone has a better suggestion, please let me know.