Replace iSight camera on MacBook Air late 2010 (A1369)
The problem with this is that in order to get to the iSight camera, you have to detach the display assembly from the body and then get the casing off, which probably means removing the display gasket and the display itself (non-trivial) because the iSight cable is routed behind the display.

You can find guides at iFixit on how to detach the display assembly (seems to be harder with an Air, it was simpler for my MBP), which appears to involve taking everything out of the bottom casing. And then you need to take apart the display. They don't even have a guide for this, you must look elsewhere (Youtube or so, but this should give you the idea that it's difficult).

Long story short: The replacement part may be cheap, but the procedure isn't, and is probably best left to a professional, unless you know what you are doing.