I received a batch of three Macbooks from different friends that were all having problems with the exact same model. I figured to could use parts from one to get at least one of the other two working again.
The first Macbook kept hanging on errors while starting up, but it only required a fresh install of OSX to boot. The second had problems with an intermittent backlight. And the third had major logic board issues and was in the worst shape, so I decided I would use that one for parts.