This is simply the most efficient way to buy the necessary equipment. Network professionals will often splice their own cable. I've always bought the best cables available from regular retail stores rather than computer stores who buy off-brand or make their own cable. I had the most trouble with unbranded cable and have often had to replace them very quickly. The simple point is that a server can be run on any computer with sufficient power and ram to handle the demands for services and connections of your network.
Servers potentially represent the greatest single cost in any network.
After all, Servers are the class of the network game. SCSI drives, RAID controllers and server boards are much desired and expensive. Usually, there are deals available for older servers and equipment. I compromised and bought an older SCSI workstation and jammed two more SCSI drives into it to run software RAID 5. The biggest problem was trying to match the older drives.