People buy broken macbooks and sell the parts. If it would have been cheaper to buy the parts and assemble it, they would've just fixed the computers instead.
You can build your own hackintosh and throw in a few "original" parts if you want? Otherwise it actually would be quite cool to have your own /whatever/ of a specific brand and model that you've assembled from parts. But in that case, it should be something that doesn't lose value by the minute, like a nice watch or a car...