Our association actually has an assignor that schedules all of the games for our association. We pay I think $50 a year for dues which is used to pay for meeting space and the assignor gets some extra money (Like around $1500 for the year) to assign and reschedule all the games.

We get to keep every penny that we are paid by each school though. The dues probably work out to about 5% for the year depending on how many games you work.