There is no option to give a discount to certain target groups or persons on a paid course. This is only available with the institution package. But if you pay 15% of the course fee to Openlearning this fucntionality should be given.
Hi Jochem Burghouts - great news! This feature is now available with an educator subscription (i.e. you don't need an institution package to offer discount codes). You can find it under Course Setup > Advanced.