Marketplace pricing strategy

I've been told building marketplaces can be hard and after thinking about the pricing strategy for one I can see why.

https://boost.courses is a mobile marketplace and web platform for creating, publishing and consuming interactive courses.

Anybody can use the web platform to create a course and publish it to the marketplace. Students can then enrol in an interactive course.

But how best to monetize this.

My first thought would be to simply take a cut of the sale value e.g.

Teacher A creates a course and publishes it on the market place for $10. Student B enrolls, pays $10 and Teacher A and Boost take a 50% cut each.

Subscription models for online courses are however becoming more prevalent now.

Do you lot have any suggestions? Or how do you prefer to pay for education online?