Comment by dangrossman

I made a WordPress plugin to add a feature to one of my own sites, and threw it up on my blog as a free download. After hundreds of downloads and comments asking for support, I rewrote it and packaged it up as a commercial product. In the next 1.5 years I made about $180,000 in profit selling that plugin, then sold the rights to the plugin on Flippa for another $90,000.