I was just informed that I have a bad SIR coil. As I have no knowledge of The airbag system, what is the SIR coil? And how do I replace it?

Also, does anyone know a place where I can get a coil from other than the dealer? I could care less if it's used or new, unless it's a part that must be replaced.... I just don't want to spend 160 on part for a car that I'm in the process of selling.

An SIR coil is used to allow the wiring for the airbag to turn with the steering wheel. It is just like the turn signal cancelling cam. It uses a band and two contacts to send the power to the airbag to inflate.
Here is a picture of what it looks like.
You probably don't want to skimp on ABS parts they are very touchy you wouldnt want the liability if the thing blew up in your face or the next owners. Buy a new one. As far as I know only the GM dealers carry them, you can buy them new for 110.00 (they do retail for 150.00)and there are two different types depending on wether or not you have radio controls on your steering wheel. Hope this helps you.