I need help in finding prices for computer processors and other computer parts?

I'm doing some research on computer parts. I need to find the sizes, demensions (of the actual product) and prices for individual pieces for a computer. I need that information on the processors, hard disk space, memory, and graphics cards. Is there one company that make all those things or do i have to investigate multipule companys? Also if any one knows of LEGAL U.S.A. Sellers of individual or bulk prices PLEASE HELP.