For a quite decent machine here are component costs as of this afternoon's US market:
1. Case
2. Power Supply
3. Fans
4. CPU
5. Memory
6. Liquid Cooling (completely optional, but cheap and helpful)
7. Primary Hard Drives (Several listed, pick one main and at least one secondary)
8. Motherboard (must be bought in concert with selected CPU)
9. Operating System - I am pricing Win 7 and Win 8 here because I hate Apple
10. Optical drive(s)
11. External backup drive.
If you shop the above compoments out, you are looking at approximately $1000 for TOP grade components, for a machine with 32 GB of memory and a total of 5 TB of hard drive storage, running one of the fastest CPU's you can buy.
If you want links and specifics, please send me a private message and I will respond with that information. I built one such monster machine for myself, and it ROCKS!
As far as putting a computer together, it has gotten easier and easier over the years. It's REALLY simple to do. If you needed guidance, I would also happyily provide my email address and phone so you could call me with any questions or even to have me walk you through it over the phone.
Bob Bone