Yeah, that’d definitely would be a good way to do it, with the payment notification.
You could post a job in a freelancers site. I have the idea of writing an add-on plugin for that, but really don’t have any estimated time to even start working on it.
One thing you could do right away, is use the email option for the notification, so s2Member sends you an email with all the data the notification has. WP Admin -> s2Member -> Notifications -> Payment -> Email
I hope that helps! 🙂