There were even fewer options when I wanted to go this route 2 years ago, so I just went with a standard payment processor (BMT Micro) and charge one-time payme

There were even fewer options when I wanted to go this route 2 years ago, so I just went with a standard payment processor (BMT Micro) and charge one-time payments for users to pre-pay for time. e.g. $19.99 for 3 months or $59.99 for a year. If you want to get from zero to charging ASAP, this might be worth considering. You could probably be integrated in a day or so. They are mainly geared toward downloadable software vendors, but I just use the "serial code" field as an Activation Code that the user enters into their profile page. BMT Micro's royalty rate is around 10%, have awesome customer service, and just added a recurring option. The main downside is limited control over the template. I would also look into FastSpring since they are newer and seem to have more flexibility with the store configuration.