I have a E39 M5 carbon black and i have broken the left rear rims (not completely broken but big damage).
So if somebody in Europe (Ileave in France near Germany) have installed new rims and want to sell the original.....email me please.
Look up on the web site WWW.AUTOBAV.COM and they should have, actually they have M5 authentic replacement rims. They go for about 500 USD a piece... i hope that helped a little. There's also another web page...i forget the name of it..i think its BECKKERS.com...they sell M5 rims also. They're both located in the US so shipping might take a little while.
I think the web address is backwards. I believe you meant to provide the address for Bavarian Autoport in New Hampshire: www.bavauto.com. They carry M5 rims but they are not listed on their web site. My catalog says they are about US$580 for the front, US$630 for the rears. Shipping in $50-$75 in the U.S. You must call for international shipping.
I'm just back from France and I checked the price of the M5 rims at the local BMW dealer. The rear rims (the larger ones) are selling for 3990 FRF with taxes. That's approximately $580. It's cheaper than in the US, especially when you add any custom duty and shipment costs.