Here is a set of Alpine HIDs for sale, size H8 bulb
I actually bought a new set of Alpine HIDs for my M3... but didn't realize that the ones from the Z4 would fit.
So I have a choice:
I can sell my used Alpine HIDs for $135 SHIPPED
Or, I can sell my New Alpine HIDs for $160 shipped
The new ones carry Alpine's full warranty
The used ones have 3 months of use, so a little less than their full warranty
Here is my thread with them on the Z4
http://e89.zpost.com/forums/showthread.php?t=433587
I'm not a pro in taking pictures so forgive me