Just wanted to check in with a success story. I bought the Wi-Fi card and PCIe adapter from the two eBay sellers listed earlier in the thread.
PCIe adapter:
http://www.ebay.com/itm/231370068228
Wi-Fi card:
http://www.ebay.com/itm/191029765954
Things arrived in a little more than two weeks from China (I'm in New Jersey). The sellers put the tracking #'s up on eBay right away, which I followed using the USPS website.
The PCIe adapter came with four long antennas (at least 6" long), and some screws that I couldn't figure out how to use. There are three antennas for the Wi-Fi and one for Bluetooth. Everything was well packed and the shipping labels were laser printed to minimize the chances of it getting lost in the mail.
I plugged everything in, using a 4x PCIe slot on my mobo (Gigabyte Z68MA-D2H-B3). Yosemite recognizes it natively and now I have Handoff and 802.11ac.