Well I answered my own question... gmpartsdirect.com breaks it down like this
switch: 92219336 $25.45
harness (auto w/paddle shift): 92236307 $31.10
harness (manual): 92236309 $38.92
It would be interesting to see what the parts guy at the dealership would want for them to see the markup. I was at my dealership yesterday and my sales guy, Patrick, called over and checked for me to see how much some splash guards would be and the lowest, with Patrick's employee discount was $170. They're $145 on gmpartsdirect. There's always some markup. I can't imagine it being too bad on the switch and the harness but, who knows. Capitalism at it's finest.