No visible airport card

Can anyone recommend a source for replacement airport card for early 2011 15.4" macbook pro?

I have updated the questions to reflect some recent updates, I now just need to find a quality replacement card and was hoping someone here could recommend one.

:: Issue stated below solved::

Hello. I recently picked up a problem MacBook pro (early 2011 2.0ghz (base model)) from a friend. We are both experienced technicians in the IT field and neither have really been able to figure out a solution to the issue. I haven't tried a third card yet, however the previous owner installed a new airport card and the OS still does not show the existence of an airport card. I have also reseated the card, and cables, reinstalled OS X Mtn lion, and thoroughly inspected the logic board for liquid damage. I have seen this issue after spills but never in a notebook in mint condition. Lastly I will add that all other aspects of the mac are working correctly. I own a second MB early 2011" 15" with the 1gb gpu, so I do have plenty of parts to swap around if anyone has any suggestions. I've googled the problem thoroughly, but I thought i'd ask for opinions before I install a usb wireless dongle. Anyone have any ideas? Thanks!

Thanks machead! So on a whim today I pulled the airport from my personal computer (the same macbook pro just with the upgraded gpu/cpu) and low and behold it works. The only thing I could figure is the replacement airport card board was either bad or has the wrong firmware or something. The card has a sticker on it that simply says "SKY"... followed by the words warranty void if removed, I'm going to try and track down the company and a warranty replacement or try another airport card altogether.