Today I've received those 2 items I bought from eBay a month ago:
NEW Mini PCI-E Adapter for BCM94360CD/BCM94331CD
http://www.ebay.com/itm/390968179409 US $13.99
Apple Broadcom BCM94360CD 802.11ac mini WLAN+Bluetooth 4.0 Wireless card
http://www.ebay.com/itm/191029765954 US $23.99
Installed on my Mac Pro 1,1 (upgraded to 2,1). The Mac had original Apple Airport and Bluetooth cards installed on it. I've removed the Airport Antennas and connected them to new card 1 and 2 positions and the Bluetooth antenna to 3rd position of the new card. (as you see the card from the antenna connectors face, WiFi to J2 and J3, Bluetooth to J1)
Everything works fine!
The adapter includes 2 cables (as pictured on eBay's item description) in case you need them for Mac Pro 3,1 or newer model.
No reason to install a 4th antenna, the reception is great and everything works out of the box.
So, bottom line is: It's nice to have professional solutions from some users here, but in case you're sure of what you're doing, make a research and save much money to grab yourself a bergain from various eBay sellers. Takes a while for the items to arrive (in my case adapter came in 15 days and card in 30) but if you're patient, you win
I hope this helps some of you who might think an investment on this Yosemite feature don't worth $100+.
Take care.