You ve got 2 main options KCI (Kansas City,MO) and there is one in Manhattan,KS that is supposed to be getting American Airlines service soon (direct flights from DFW dallas). It s a bit of a drive from Kansas City but shouldn t take you more than 2 to 3 hrs. I ve got to imagine its expensive to fly into Manhattan though.
Kansas State University is about is about a 2 hour drive to Kansas City depending on traffic, so your answer would be Manhattan Regional Airport in Kansas.
Probably KCI