Here is the kicker with PSU. Paterno barely made over a million from the university. He made boat loads in other places but that was because of his legacy, PR couldn't get that right away.
I don't think PSU is looking at paying 3 million/year for their next head coach. Anything less than 3 million is not worth leaving for right now.
All in all, PR doesn't leave ISU for PSU.
You can't base Penn State's pay scale based on Paterno. I'm sure Paterno was the one that didn't push for pay increases and was more than happy with his salary. Penn State will pay north of $2.5m if they get the right guy because they'll have to. They have to know that the last thing they need now is for their football program to start losing consistently.