I've had my laptops apart numerous times. I've replaced screens, backlights, touchpads, keyboards, optical drives, graphics cards & motherboards. Most parts bought on eBay, either as discrete items or a broken laptop that is OK for the part(s) I want, and others OEM new. Some laptops are easy to pull apart, others really need a field disassembly manual to make sure all the right bits are unfastened in the correct sequence.
My current laptop, an early 2002 Satellite 5105-S901, is called 'Frankenputer' on our home network for good reason. I managed to tread on it while preflighting an aircraft one morning and broke the screen. Bought a slightly lower spec carcass off eBay and used its screen for mine and it's keyboard for my wife's matching lappy. Over time various other issues have developed between our two laptops, leading to a new lappy for the missus while mine has become a combination of all three 5105s. Motherboard & video card from the eBay carcass, bits from Pax.D's one and other parts from my original. Not bad for an 8 yr old laptop although I think its in its twilight years.