Don't forget the importance of key volunteers that support the DE program, even though they may not be instructors. Without a good foundation of volunteers, the event cannot happen.
FWIW, volunteers that step up are recognized, and can make the difference in tie-breaker decisions for the last few remaining spots. I've always encouraged new folks to take advantage of the volunteer opportunities to help keep the program healthy, as well as meeting many of the key players. Its no guarantee, but I know of many instances where a wait-lister opted to come out to the event anyway, planning to help out, only to find themselves being able to take advantage of a last minute cancellation.
Of course it helps if you arrive prepared, including a Tech Inspection Form, helmet, appropriate clothing, etc.