I would contact Steve Haygood of Automobile Solutions. Steve is the BEST around for OEM parts. He will sell it them to you for as cheap as he possibly can. You can contact him at (706) 647-1485. Mention that a MyE28.com member sent you.
If he can't get them cheap enough for you, there's an ebay seller that goes by the name FCP Groton that has pretty good quality stuff. I've used his parts on my e28 and have been satisfied thus far, as have others that I know.