Here is a completed build I did to replace a small tower at work.
This will host a Windows 10 VM, running Quickbooks Server.
It will also be a file server for the office.
I had Unraid running on the office desktop that had been repurposed into the server, and the neat thing about this, is that I simply swapped the USB stick containing Unraid and my drives to the new hardware and Unraid booted right up like it was always installed there. All I needed to do was start up the array.
I plan to add dual parity and dual cache for this use case and will expand the storage, as well.
Let’s get right into it.
Specs and Prices
Case - Cooler Master Elite 350 w PSU -------------$82.79
Motherboard - Supermicro X9SCM-F--------------- $49.99
Proc - Intel Xeon E3-1260L 2.4GHz Quad Core- $39.20
Ram - 8G 2x4GB PC3-12800E ---------------------$25.95
Kingston 120GB A400 SSD - Cache -------------- $16.99
CPU Cooler - Thermaltake Gravity i2-------------- $9.98
HDD WD Blue 1.0TB - Parity ---------------------- Reused
HDD Seagate 250GB ---------------------------------Reused
Total ------------------------------------------ $224.90
Photos!
Cooler Master Elite 350 with PSU and parts included:
Other parts:
Processor in the socket:
Thermaltake Gravity i2 installed:
Rule 0:
Checking the BIOS settings:
Relax, they’re just standoffs anyway.
Sitting on the new perches:
All wired up.
Proof of life:
Thanks to all here for the inspiration and help to roll my own. I have always used retired Dell servers in the past. I have built plenty of personal PCs over the years and this was, by far, the most enjoyable.
Cheers! 
OT
P.S.I will be posting again when I finish tidying up my home server that I just also completed, which I am quite happy with.