Unlike a PC, the hard drive from one MacBook will probably work in a similar Mac just fine. One of the repair options we can offer our customers is what we call a shell swap. We can take the hard drive, memory, battery, or other parts out of your broken MacBook and put them in a working "shell". You have all the "stuff" your MacBook used to have, and we just put it all in a working computer.
We have done shell swaps numerous times on older MacBooks with problems. The cost of parts and labor for repairing some of the older machines is high, and we can deliver far more value to our customers if we can simply put their hard drive in an affordable replacement Mac. For instance, you have a 2007 White MacBook and your hinges are broken. Repairing or replacing the hinges is a huge amount of labor. The cost of repairing "your" MacBook would be higher than the cost of a working older MacBook.
We have in stock many fully functional older MacBooks and can help just about anyone with problems with their older Macs. If you bring in a broken MacBook be aware that we can in many cases put your have drive in another machine, and give you some credit for the parts from your broken MacBook. Win, win.