However, there is still an economic case to be made for building a server. At my place of employment, for example, I recently built a server for roughly half the cost of one sold by a major manufacturer with the same exact specs.
In addition to saving money, building a server also gives you a final product that is free from proprietary parts, so getting replacement parts is easy. With many servers offered by major manufacturers, the only way to to ensure that you can get replacement parts in a timely fashion is to purchase an expensive service contract.
The video you see on the right shows the process of building a server designed to run Proxmox VE and host virtual servers. I built this as a side project for a local non-profit organization. It hosts four Linux virtual servers, three of which run all the time and one that is used from time to time. Below is a list of the parts I used for the server built in the video:
Case/Chassis: NORCO RPC-231
Hot-swap drive cage: iStarUSA BPN-DE230SS
Power Supply: Topower Zumax ZU-650W
Motherboard: Supermicro Sever Motherboard H8SCM-F-O
Processor: AMD Opteron 4226 6-core, 2.7GHz
Heatsink/Fan: Dynatron A86G
RAM: Kingston ValueRAM 8GB KVR13E9/8I
RAID Controller: Adaptec 2260200-R 2405
SATA Cable for RAID controller: 3ware CBL-SFF8087OCF-05M
Hard drives (2): Seagate Barracuda 2 TB ST2000DM001
If you have questions or comments, head over the the video above and leave a comment or question on Youtube. I do a better job managing feedback on Youtube as opposed to here on my blog.