The "cheap" comment by you here is unfair. The "diamond in the rough" model you describe produced Campbell and he has been and will be paid accordingly to keep him at ISU. As with Fred, if Campbell leaves ISU, it won't be primarily due to money.
The timing of Fred's departure significantly restricted the pool of interested and qualified candidates at that time. Gregg Marshall is the only high dollar guy I am aware of who expressed some interest but I doubt he was truly serious (ISU certainly wasn't the only program he used to poach more money from Wichita and the Kochs). And he obviously was far too toxic even back then.
JP doesn't need to hire a +$3M/yr +60 guy like Beilien, Sampson or Altman. Beilien is done with recruiting, Sampson essentially has a family business set up at UH (with Fertitta resources) and isn't going anywhere and Altman has too good of a gig at Oregon and a big buyout.
There are real good "diamond in the rough" candidates that would leave their current gigs for ISU for $2M/yr. Otz is amongst those even with his big UNLV buyout that will need to taken care of by you know who and others. Craig Smith, Luke Yaklich and Darian DeVries also need to be on the short list and one can argue they all have as much upside for ISU as Otz does.
If you knew how the last MBB coaching search and discussions went on the inside, you would call him cheap. Period.