For what it's worth old Drobo 4 bay units go for around $60-$80. They are flawed systems for sure but they are absolutely better than the cheap 4 bay units and their software raid implementations you'll find on Amazon and Newegg.
Throw in the 4 largest drives you have and see what you get...
Save as everyone else above. My 2600k system with 980ti/mobo/16gb RAM/Raid-0 SSD's is still fast enough for my 60hz/1200p monitor. Thats the limiting factor. A new monitor would drive my upgrades at this point, not cpu pricing.