This is a very helpful thread, and thanks for posting it.
I was always dissapointed that GM hadn't fitted something a little more.
After reading this I did some searching.
It seems that ACSCO make these for different cars, and not just GM.
I was able to find a KIA unit that looks exactly the same but with 4 cupholder LEDs for USD $35 from Parts Brokers
http://www.ebay.com/itm/NEW-OEM-AMBI...-/262584075534
Apart from the power lead, and a metal bracket riveted to one footwell light, the other parts look the same.
So while I appreciate the "GM parts" bit, it seems they buy from a supplier and have them marked accordingly.
Mark