We did a test with our academy account on facebook. We purchased a facebook add and it gave us a lot of new referrals and points. We spend a little over 40€ in 3 days to get 4 free courses.
This means that each course would have cost us 10€ and not 55€ which is the regular price.
See the screenshots
This is the add
These are the leads and number of free courses
You can run adds also if you are commision based.
The best results are to share the forum topics. They get the most visits