If you're new to biking, and, as you say you are, unfamilar with what are good or bad components, then I would say do not even think about building a bike from scratch. There are so many things to think about, and like Raiyn says even if you shop for deals you won't match the price of a pre built.
Check out advice given on this site for good starter bikes and then upgrade as you go along. Specialized seem to have a good rep among members, and it seems to me like a heck of a lot of people out there are riding hardrocks. Not my cup of tea, but they must be popular for a reason.