For each of my cars I have been able to buy an inexpensive OBD-II to USB cable and find some comprehensive dealer scanning software online. I've never spent more than $40 for the setup, and being able to scan codes on my own (as well as do some programming) has been very useful. There will be a Kia owners' forum somewhere with relevant info if this is feasible for Kia vehicles.
If you're lucky the airbag light will have been tripped because the cable connecting the occupancy sensor mat in one of the front seats has been disconnected or frayed. This is a pretty common problem on a wide variety of cars. If you are less lucky the problem with be with a crush or impact sensor, the ABS module itself, the steering wheel slip ring, or one of the 'bags (least likely).
I bought an '01 Ford Focus from a friend a few years ago. It had failed its MOT (state inspection) because the airbag light was on. A £10 OBD-II cable, some Ford scanning software and a £35 used SRS module later and the car was roadworthy again. A dealer would have charged at least £700 for the work using new parts, though.
On a more serious note, airbags can be rather dangerous, and it's not unknown for faults to cause them to deploy/discharge unexpectedly. However you choose to have the problem diagnosed, do it soon.