Ironically, that's a good business idea for someone: 'MonetizeMe.com' It would be a company that specialises in taking a working web-app and setting up the pay

Ironically, that's a good business idea for someone: 'MonetizeMe.com' It would be a company that specialises in taking a working web-app and setting up the payment gateway and other details necessary for making it a commercial endeavour. In return they get a slice of the profit or something. While the original developer doesn't need to endure the headaches of commerce to reap the benefits.