These systems have been available for several years now, so I don't really see how many people would buy a retrofit option. People don't even upgrade their car stereo systems anymore.
That's because the manufacturers tie so much stuff into them. It's been 3 years since I looked into it, but it was my understanding that if I upgraded my stereo I'd lose the nice display just below the windshield line. I think I'd also lose either the steering wheel music controls, or the bluetooth controls for my phone.
