Currently Being ModeratedJan 5, 2013 5:52 AM (in response to haiduy)
Apple does not have an exchange policy.
You can sell your computer to someone else and buy a new one from Apple.
Currently Being ModeratedJan 5, 2013 8:27 AM (in response to haiduy)
You may also find that an Apple Retailer will buy back your 2011 MBA IF you buy a 2012 MBA from them and if you have been on AppleCare.
The current pricing at my local Apple Retailer is 50%. but you might be able to do better with your Retailer or privately.
CheersMacBook Air (11-inch, Mid 2012), OS X Mountain Lion (10.8.2)