I think anything officially coming from the NCAA would have to have some sort of Title 9 considerations. I don't know if Title 9 insists on equal shares of everything or if it can be adjusted for relative revenues.
Things that are earned outside of the NCAA or school - such as the example of an autograph signing at a local car dealership - I would think would not have to be equally offered to everyone. That's an individual thing from an outside entity.
That said, I've got no idea exactly how Title 9 works, so entirely possible there are major complications which would make this exceedingly difficult.