MBA wifi busted - can I just install a USB Wifi dongle?
I don't think it is that easy: isn't a working Wifi Airport Card a prerequisite for connecting/authenticating with the App Store?

On my MB Air 2,1 (mid 2009) the wifi is broken. Connecting with the internet is possible via an Apple USB-Ethernet-adapter but when trying to install an App/update OSx El Capitan the message in App Store is:


  Your device or computer could not be verified.


I've googled a bit and as far as I can tell the options for this 5 year old machine are either to have the wifi repaired (€125) or buy a USB wifi dongle (€22) and accept that OSx will not be able to update. 

E.g. this post:


  A NIC (network interface card) is needed for authentication purposes to make sure the computer is what it claims to be.


on forums.macrumors.com reads like a sound argument. 

On Hackintosh this seems to be fixed with various work arounds - but that's too much tinkering for me.