I teach some on-line classes for a community college, generally two per term. The upfront costs were pretty steep–learning how to use the software, writing up on-line lectures and quizzes, etc. Everything takes long in the course software than it does for a regular class, just using MSWord (or, for my lectures, just having a rough outline of notes). The first term didn’t really pay enough to be worth it, but the big payoff comes in the following terms when very little work has to be done. Unless I change the text (or it changes substantially), the only “capital” costs are changing the due dates for items. And I’ve learned how to structure the course so my “operating” costs are pretty low.
Then they changed the course software on me. I’ve spent at least one week of full-time work, perhaps more, training on the new software and transferring everything over. So this term I’m back to just recouping my capital costs.