We are in ST. Louis, MO and I have usually found SouthWest Airlines to our best bet. I usually get them for under 99.00 each way. Flying on a Tue or Wed is cheaper so we usually go Wed-Wed. They also don't charge any checked bag fee.
Last year before those fees were added I found a great deal on American Airlines ($75.00 each way- now that same fare would be $115 w/ 2 checked bags)