Yeah I've already tried to buy one of the mavids ones but they go in and out of stock so quickly I've lost my patience with it.
I don't mind the USB port thing as I was going to buy a USB 3.0 PCI-E card anyway, I just wanted to see if I need a specific thing to be compatible with the OSXWIFI card.
I am from the UK so sending back isn't quite so easy..
Gotcha, you'll be very limited in choices for USB 3.0 with internal ports, but there are a few, especially if you don't mind rigging up an internal power connection. I have an Orico card that has 2 internal USB connections, but it requires additional power to be split off from one of your drives. It uses the FriscoLogic controller so it's compatible with most everything. Amazon carries them.