You forgot to factor in a server-grade motherboard, and the price of the specialized intel compiler into that.  Lets say the device itself is your only cost.  Even then, you're getting 57 threads at 1.1 GHz with access to 8GB memory at $224 pulling 300 Watts.  Compare to a radeon r7 240 4GB, with 320 threads at 1.1 GHz with access to 4GB memory at $80 pulling 25 Watts.