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You could go to an Apple store or call Apple support and ask how much a similar repair could cost possibly. Typically though their repairs are pretty expensive, so I would make sure you know what you're getting into before you buy it.
 
I wouldn't buy this just to save 100 or 200. You can get a brand new Air around $1400 if you shop around.
 
You're probably not going to save anything if you have to pay Apple to fix it, in fact you may come out worse.

But if you can do it yourself, you may be able to find the part online somewhere and save some money.
 
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