There are some rather rare option groups, some of it is just luck. Mine was custom ordered with nothing but the side airbags/rear sensors, and I almost never see 300Cs without the SIRIUS antenna lol
I don't really think having a specific radio is going to make a difference - these aren't 250 unit production Challengers or Barracudas. You might see demand for them 50 years from now like there is always demand for the 50's era Chevys. (Who doesn't like 57 Bel Airs?)
But will people 50 years from now think a 300C is cool? Right now everyone and their brother wants a BMW of some sort anyway. Shoot, 50's cars and muscle cars are a bit of an acquired taste... I don't think teenagers get into it unless their parents get them into it.
Most people I know in my classes have a Civic or some other annoying little Japanese car and aspire to own a BMW M3. *sigh* The lucky guys have a BMW or a Subaru WRX, and then I'm the crazy freak with the only 300 in the science parking lot at my campus... As of late there's a purple and black Charger RT as well :O Every now and then, I also see a green Charger, but that belongs to someone in life science (and that's.. a different thing).
Usually if I see a 300, it's one of a few bling'd out 300 V6s in the business parking lot. XD