Completely useless until when they release the design of their board under public domain. Firmware included. And I wanted to see both the evo and the new half costs version.

Even after that, you would have to add PSU and cooling. $200. And you are being optimistic in your per board cost. $300 is. You could probably reach that price if you had the PCBs for in hand for free. So $300 + $168 + $200 for 650GH. Plus the yield, plus whatever could go wrong since that you will have to deal directly with suppliers. Good luck.