because it's expensive? On ebay you can get them from what i have seen from 50-100 punds + postage. My mod cost me 2 diodes a few wires (not more than 1€) and a few hours of work. Mybe in the future i'll buy it but will probably bought a new focus with autoheadlamp instead.
I like to experiment and try to make my project as cheap as they can go...with the same results as they have been original bought.
Mybe for offtopic i have salfemade xenon headlamp controler with working original xenon leveling sensors. All dow is not 100% fully working (calibaration needed) but 1st project results are good.
I was on impression that there are some intusiasts here that have some familiar projects and ideas so that's why i'm writing on this forum...or it's another "help me...and never see me again" forum.