Water damage - what to do?

I have a Macbook Air that is about 1.5 years old. About a week ago, my wife accidentally spilled a couple of ounces of spring water on top of it (it was closed and in sleep mode). I didn't use it and let it dry, thinking that might save it - also believing that water didn't get into any of the ports. But the Macbook won't power on or even charge (the LED light on the charger doesn't even turn on). I took it to the Apple Store today and was told that the logic board has a tiny amount of corrosion on it - the tech said he didn't see it at first (it was that small) - but that it would cost upwards of $750 for a flat-rate fix.

As you might have guessed, we left with the laptop not being repaired. So I'm not sure what to do. Should I attempt to tear it apart and clean the logic board, hoping that that fixes it? Should I sell it on ebay for parts only?

How likely is it that there would be a lot of water damage if the tech could only find a small amount of corrosion on the logic board? I guess it's impossible to tell until it's done, but how hard is it to do this? What tools would I need? Do I have to separate the CPU from the logic board?