Seeking advice from sifus here.

Its been a long time i did not build a custom cpu.. now i want to build one for the purpose of: 1. As my data storage, 2. As a processing workhorse for my work data analysis

To build a cpu from used spare parts, how much do you think it will costs for below requirements:

1. CPU: intel i7 (4 cores) clocked at least >2.0ghz
2. 8gb ram
3. Graphic card: decent, i wont play game on this, just need a card that can serve the monitor modestly
4. Motherboard that can accommodate item 1-3 above
5. Power supply, a decent and reliable one. I dont want to risk the cpu blow up obviously bcoz i will keep data in it
6. Hard drive, a small but efficient one is enough.. most data will be stored in my external
7. A simply casing but enought to efficiently accommodate the above

How much these will totally cost? Any suggestions?

Thanks in advance