The ones I have aren't OEM. They look like these
http://www.ebay.co.uk/itm/BMW-Brand...906833&hash=item237d943845:g:VHkAAOSwoA9ZfAGs but nowhere near the price!!
I think I paid about £100. I'll see if I can find the place that did them again as they're not coming up on ebay and ebay wont show me far enough back in my purchase history (Too many purchases!! lol).
I made a quick video a while ago with them and my elight module for programming the headlights and rear lights to come on with the key. I still need to hide the red wire.
[youtube]3qAt285DBng[/youtube]
They were ok to fit, but I'd already previously retrofitted footlights to come on with the interior light so I wired these up the same. I don't know if you have footlights already but they were a bit of a pig to do trying to find the right wires. Every guide and post I've read had different coloured wires to use and mine were different even still! Having said that I'm not the best electrician so you could probably do it in half the time I did.
I followed the guide for Z3 footlights on Leatherz.com as it was pretty similar. And I couldn't find a specific step by step guide for the Z4, or at least one I could really understand.