I bought a new radiator for my 2800 CS from Mesa Performance just last month. It cost me $300. While my old one wasn't that bad, I figured that if it cost me $150 to fix it, and it lasted 3-4 more years, I would be better off investing in a new part.
The sticker on the top of the radiator reads: "Behr RC08 30, Kuehlmittelkuehler, 700111200, Made in South Africa"
Spence at Mesa commented that an e9 radiator is identical to the one used on the later e_ (sorry, I didn't pay attention to which later BMW model he named). However, BMW documentation shows different part numbers - and different prices - for the e9 and e_ radiators. And yes, the price for the e9 part number is more. So, your local BMW dealer can no doubt get a radiator that is the exact replacement for your e9, but if you want to save some $$, you'll need a clever parts guy to tell you what BMW model to ask for.
Abe: You're just in Thousand Oaks - you might call Mesa (949 642-8824) and see what shipping would run if they get it for you. Or, drive on down to Orange County.