Also, if you have to be at the sports complex for early morning, I am guessing that you are participating in some sort of Disney sponsored event. If that is the case, there may be transportation available for you. (I.e., the marathon...although I was a volunteer, and I had to get a cab to my station...had to be there before the buses for the runners started).
Otherwise, VAgal76 (Hi B!) is correct a cab is probably cheaper than a van service.
Lynn