1. Step: Create a software and sell it (or give it away for free). 2. Step: Offer to create add-ons for that software. It has been working fine for me for a c

1. Step: Create a software and sell it (or give it away for free). 2. Step: Offer to create add-ons for that software. It has been working fine for me for a couple of years now. The software is B2B and the customers are mostly small businesses. I get a couple of feature requests per week from those existing customers. And not only convert those requests quite often to new projects, I also get to offer the add-ons to other customers. That's always part of the agreement. The costs of the add-ons have been in the range from $250 to $2000.