When I taught a couple of classes one was leaning towards Self Development and Personal Growth and the other was Community Development for Non-profits organizations. It was back before blogging became real popular. I wrote articles on the topic nearly every day from 2005 to 2008. Both classes were under 40 bucks and I earned about $11,000 over two and half year period. What I learned from the experience is you have to use content marketing to sell your content unless you have a budget for Facebook Ads and PPC. And we know how costly that can get. In other words you have to create a lot of free valuable content to sell your paid content. That seems to be the game.