Sehr gut! Du will lieben deutschland
I lived in Berlin for the month of March and its fantastic. Make sure you to the New Berlin pub crawl when you are there! Right by Oranienburger S bahn station - every night at 8pm
I went to a handful of bmw "autoverwerter" junkyards and it was hit and miss. They either didnt have any old e30s lying around, or the holy grail of bmw teile (parts) in berlin I searched for hours around an industrial park not finding the address. Naturally the phone number didnt work either....
I hope you speak some German since most of the grunts at these places dont speak a word of english, although at the dealer you should be fine.
Headlights are "scheinwerfer" in german
Pick up a copy of Zweite Hand (at any newstand) in Berlin, and check out the section BMW Teile. Its like a pennysaver type magazine, but there is a fair number of people parting out e36s etc, privately, so you might score some better prices too.
Good luck and have fun!