You're a business guy, so I know you get this, but this the sticker cost of a year's tuition isn't anything like the actual cost. Most, if not all schools, play a little game every year with the number of applicants they have, the number of accepted students, and number of students who plan on attending as well as the number of those paying full freight (typically foreign students). If it's looking like they need a 100 additional students to accept, they'll discount the nominal cost through grants and financial aid to increase enrollment. The numbers they worry most about are enrollment and actual revenue.
Most of these schools are run by MBA types with eyes very much fixed to the bottom line. The flow of funds from the AD to the school's coffer is pretty much a straight pipe. Student athletes are billed the full freight cost at sticker and the AD funnels the TV money to the school. If they could charge student athletes more, they absolutely would.