here is one that i have saved its a little over your budget but as I built it on the uk site maybe there are some cheaper options for you from U.S retailers
It has only 2 USB 3.0 ports on back, you can install at least 5 HDDs on it, however concerning the build I've realised the fx 6300 will bottleneck your r9 290, to upgrade to an fx 8350 and an 990fx mobo will be costly: