It was a long time ago, and it was Java programming/certification courses. At the time I had a high Google ranking so I figured I could get the audience. In fact the terms java programmer certification still rank my page on page one of Google. Down a bit from when it ranked higher than the inventors of Java. If I was still playing that game I would be offering Android development courses.
I used adsense (in fact I am the maintainer of the Moodle adsense block which I picked up from another developer though it is a long time since I did anything with it).
I figure it is easier to start with a high price and come down/offer a discount than up the price later on.