I'm interested in the C350e and like a nice stereo, but one thing I'm keen to avoid is the higher rate of VED. The Burmester upgrade sounds like it could be rather wonderful, but takes it over the magic £40k level, and for half that kind of money (and I don't particularly want the other bits that come in the package) one could get a pretty decent third-party ICE system installed (I'm probably just thinking just amp and speakers rather than replacing the head unit). Has anyone here tried this? Do MB make it difficult? Assuming that they don't, how much is a "sensible" option likely to set me back?