If you're looking for a cheaper way to get real xenons for your Benz then the offered Phillips for $599, I think you have to search very well!
I myself own a C-class as well and changed about every possible part of it (I went from a 1993 classic to a full-optioned 1996 sport-//AMG). I thought about putting xenons as well and I must admit that the light of xenons is way better then the standard headlights (my father ownes a E-class with xenon lights and the difference is very big).
Despite what manufacturers tell, the xenon bulbs tend to stop illuminating to often and sometimes to quick in stead of lasting a life-time! Replacing these bulbs is about 10-15 times more expensive as changing the standard Halogen bulbs.
If you want to install xenons, you will be needing some wiring and whipers as well.
Anyway, I decided for myself that the costs were not worth the effort although I already put in the wiring for the xenons and wipers in my car.
by the way: I've seen your name on mbnz.org several times as well concerning this issue...
with a minor 600+k