You can go the eBay route for this stuff, which will be cheaper...
I got a 3 window type SIC module from eBay over a year ago for $120. I got it working (electrically) on a Calais V, but decided against using it, as there were too many trim peices to change,
(I have the cream interior, and the sports modules didnt come out with this colour).
The Colour HVAC/Radio modules go for around $400-$600, depending on condition, etc.
If you have an EEPROM programmer, you can program it yourself to work with your car. (Requires setting the VIN number).
You can also change the startup screen logo (Holden, HSV, Caprice, Chevrolet) and the text colour to match as well using this method.
This page,
www.carmodder.com • Programming the Colour LCD HVAC / Radio for the Holden VE Commodore
Describes what you need, the EEPROM programmer specs, as well as the EEPROM locations.
The EEPROM programmer and the 3M clip will cost you around $60 from eBay.
Hope this helps