If you could get viewer data on all sports you could almost do allocation by eyeballs - basketball, baseball, tennis, volleyball, and soccer are all on SECN, plus the golf and T&F championships. But, I think that would shortchange smaller programs unfairly.
Athletic Dept overhead could be allocated by # of athletes. Divide overhead by total # of athletes, then allocate to each program by number of players on the roster. I wouldn't recommend budgeting for our sports this way, but it would give a clear picture of costs and revenues.