BMW yes - marketting NO, I wouldn\'t know this much about the ICE system or Electrical system!!
unofficially:
The radio costs 120 quid - piece price. The tooling for each faceplate (so there are 4 of them) cost about 200 000 quid each. The cost comes in when you integrate different sources, like Navi, DSP, Tel, Aux, TV, Video, Headphone output, CD cahnger, Steering wheel controls etc etc.
Aftermarket units are not fitted for a number of reasons. Most importantly they are not reliable enough. The cost of unreliable radios is phenomenal, as any Rover dealer, Rover ICE engineer. Also aftermarket radios would never pass the vehicle tests (vibration, hot, cold, humidity etc. 1 Radio for Mini must go everywhere, not just Japan, USA, UK & Europe, where virtually all sales are made on Aftermarket units which you see.
Sorry, I have to tell you that you are wrong on this one.
The other point of discussion is Power -There is just no way of telling the actual power of a 4x40W aftermarket unit. I keep getting asked the power of Mini radios, but I can not seem to get and give a definative answer. Its a nightmare