While I am also disappointed that there's only one in KC, there are other options. For one, you can try 5013's Drive Hard event (
https://trobots.org), or you can try a close by off season. KC FIRST's calendar has a few listen on that for October (
http://www.kcfirst.org/events).
Just like you, though, we just go to Cow Town every year, or at least that has been our plan so far. We plan on going to Drive Hard and potentially another off season, but that's yet to be determined.