Enrolment

The courses that we are going to deliver would mostly be used by volunteers. This PayPal (module?) got me thinking.
We do not give free training - we give training in turn for some volunteer work.
How difficult would it be to have something similar to PayPal to check how many "volunteer credits" a prospective student has and based on that whether or not to allow him/her to a certain course ?

Just thinking aloud....
Riaan