I replaced all 4 of mine.
GM part numbers:
1999442 - Radio program and source buttons
1999443 - Radio seek/volume
21997738 - trip/fuel buttons
21997739 - personalization
MSRP on all 4 switches is $100.70
All 4 are pulled out with a screwdriver. The top 2 you can get to with a screw driver and pick if your real patient, only because the wires are BARELY long enough. The lower 2 you have to pull the steering wheel.
Instructions for pulling the wheel are here...
http://autowoods.com/2003_-_06.htm