That's what I was thinking. Off the top of my head (not 100% checking compatability, but with current Newegg prices), to replace my current machine, not counting the 24 inch 1080p monitor (which in my experience last a long time as long as a tornado doesn't throw rocks into them (really)) and keyboard, mouse, etc.:

  Supermicro XnSAE workstation motherboard: 215
  3.3GHz 4 core Xeon E3-1226 CPU w/HDMI out: 217
  32 GiB DDR3 1600 ECC Kingston memory: 240
  Low end 1/3 w/year for 5 years data center 80GB Intel SATA SSD: 100
  Seagate "enterprise" <550/TB/year 4 TB hard disk: 210

982 USD plus shipping plus whatever enclosure, power supply, high quality fans etc. you put into it, which ought not go over $200 new. E.g. after discovering a Lian-Li enclosure I love I bought 3 more and cycle through them.

Plus backup, however you do that (make sure critical stuff is offsite!). And, say, a man-week of your time to configure, order, build, install and configure Linux. The result will be very fast and rock solid (well, if put behind a good UPS) workstation class machine with a 5 year design life.