get it from getbmwparts.com
They have the waterpump, bolts, and thermo stat for $425 shipped with the July 4th promo coupon. I think it's fireworks4 or something. Check the vendor section for the codes.
EDIT: Here are the links.
http://www.e90post.com/forums/showthread.php?t=681983
http://www.e90post.com/forums/showthread.php?t=859676