For replacement parts, I would find the part# on realOEM.com and then use www.furiosmethod.com to find the best price.
For aftermarket mod parts, we don't have much support from the manufactures anyway. So it's a little more tough, especially those with better quality.

__________________

00 E39 DINAN S1 //M5 (82k miles)
06 E53 DINAN 4.8iS, born 2/18/2006 (126k miles) http://www.xoutpost.com/bmw-sav-foru...s-my-dslr.html
90 Straman Z32 TwinTurbo Convertible, (1 of 44 ever made) 5 speed, 444rwhp/451rwtq
01 360 Novitec Spider F1 (26k miles)