Totally correct in that they have completely phased out the dealer installs. Used to be the only way one could get OnStar.
With the current Gen F1 system, it is extremely more complex than the original Delphi systems. Each individual vehicle has to be programmed much in the same way that a VCM/BCM is programmed. Due to a lot of the information being proprietary, it would be a hard sell for Motorolla to allow the retail access to the module.
Additionally, with all the different content, it would be almost like asking the dealer to re-manufacture the vehicle. For example, some vehicles come with the microphone installed into the headliner....and not many dealers are going to cut a hole in the headliner. Wiring harness are different, no coax run for the cell or gps, and drilling the holes in the sheet metal for the antennas......a potential warranty nightmare for corrosion/water intrusion.
Interesting topic on the cellphone usage. The ESN is recorded on the box in Hexidecimal, which can be converted over to numeric. When I was at OnStar, they were primarily using Verizon Wireless for their carrier......so Verizon has the ESN in their system already, just like if you buy a cell phone from them, they can set it up rather quickly. However, I think OnStar has a contract with the carrier that identifies it by the MIN (the telephone number) that says OnStar can only implement cellular service as a third-party biller.
The reason the cost is so high is due to it being an all AMPS (Analog) service. OnStar had to stick with AMPS to assure coverage as there is not single CDMA/PCS signal that covers the entire country at the time of implementation. The newer models will come out with both AMPS/PCS (Dual-band) to counter this and will be a bit cheaper to get minutes. Also, there will be an option to have a portable handheld that is syncd to the MIN so that both the portable and the OnStar unit will share the minutes. Plus, be able to access OnStar services from the handheld if you are within service range from the vehicle. Add to that fewer dropped calls if within distance of your vehicle as the 0.6Watts from a normal cell phone only has to be close to the truck, which uses a (if I remember correctly) a full 3Watts.
Back to the topic, rates will get a bit of a discount the closer one comes to service being dropped. However, it will never be "cheap" until they switch to digital service.......