Comment by andrzejkrzywda

It's not a classical open-source project, but what we did with our React.JS koans (and other our OSS repos) was to advertise our React.js book in the README and give a discount code. Essentially, it's an ad for our own book.

https://github.com/arkency/reactjs_koans

Thanks to this solution we've had more money to work on this and other OSS projects.