I ordered the correct one here:
http://www.ebay.com/itm/200910020950?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
It says BCM94331PCIEBT4CAX in the title, and shows it in the picture.
as for the OS-Store listing shown earlier in the thread, I mentioned a while back that the one in the picture is not the correct one, in an attempt to warn other buyers. I did not buy from os-store, but the picture on their listing clearly shows without the CAX, it shows a 607-7291 and does not show CAX in the listing.
The link I posted is even three dollars cheaper. I ordered on July 7th and got it (from China) on the 10th.