One option is to provide dedicated support while letting the code be open. There are plenty of businesses that run on open, freely available architecture, and they make all their money by selling a "Pro" plan that allows people the security of being able to pick up the phone and ask a question. However, you have to give away your product on the front end as a loss leader. This is essentially the "Insurance" business model. It's how Circuit City rose and fell. Be careful, and good luck.