Oh really? I guess so, I did buncha searching around not too many options available to make your own laptop. Why is it like that?
I guess because parts are expensive and few and far in between, need to fit certain mobos and most of the times need to be soldered to the mobo. Assembling the case after putting together the system is another PITA. That's why people prefer not to deal with this. Manufacturers have special tools at their disposal and that makes their lives a lot easier. To build laptops (esp. if wanting to sell them for profit) is not feasible for individuals.
The sheer amount of labor involved in, say, servicing a laptop makes it a costly proposition for customers, as well, if they are outside warranty and have to pay for that themselves. I know someone that was charged about $100 for a simple power plug replacement, with no warranty after that either.