Unfortunately because there aren't a lot of used OEM ones floating around, you'll probably have to buy them new from the website I linked above for €139 each. They're a Bosch part, probably made right down the road from the Spartanburg plant in Anderson, SC.

As for the LCI retrofit kit, no price is listed, so I'd have to ask contacts in Germany for the cost from their dealers.

eBay Auction

http://www.bilder-hochladen.net/files/70d4-1b-jpg.html