For less than $500 you can find dual E5-2670 1U or 2U servers on eBay. Very very hard to find a better value.
http://www.ebay.com/itm/ZT-2U-Storag...-/152186550866 this thing even has an LSI RAID controller in it! Or
http://www.ebay.com/itm/1U-Rackmount...UAAOSwzJ5XYegy this one still under $500 comes with an SSD to boot. Hope you have a basement to hide it though because these are loud.