The conference still has all-session tickets available, but they are all uppers. You can get one of these for about $300 after fees. This includes five sessions.
If you are interested in just going to the sessions where ISU plays, you will have to get them through a ticket broker like StubHub or from a scalper near the arena. Regardless, the tickets will be electronic.
There are lots a variables on which route is cheaper, such as 1) how far ISU progresses in the tournament (they would play in three of the five sessions at the most), 2) whether ISU is in KU’s bracket, and 3) how far KU and KSU progress.
If ISU plays in three sessions, that is, they make the championship game, the cost of buying three sessions from a ticket broker or scalper could exceed the cost of an all session ticket. However, once again, this will depend on the aforementioned variables. It’s also conceivable that the cost of the three sessions could be similar or slightly less than an all-session ticket if ISU is not on KU’s side if the bracket and they never play one another.
For what it’s worth, I am going down and plan to just buy the sessions that I want to attend. I have been to the Big 12 tournament over a dozen times and have always done it this way. As a result, if ISU gets beat on Thursday or Friday, I don’t have to worry about unloading tickets for the remaining sessions. On the other hand, if you love college basketball and want to attend all sessions, regardless of whether ISU is playing, I would opt for the all session tickets.
Hope this helps.