There are barebones laptops which basically require a processor, ram, hard drive, wireless card(if needed)... In the end, it's probably more expensive than simply purchasing a regular laptop.
Please use the search this has been talked about many times
And i would like to claim being the first one to bring it up a few years ago...
Soo much is intergrated in a laptop, there wouldnt be much to do...push in ram...maybe add a hd or cpu...but then again, i guess the only difference between that and a pc is the vid card...so i take that last statement back.