I wonder if just selling one board and you have to make your own enclosure and cool it your self would be viable.
Strapping a board to some wood and pointing fans at it is quite easy for anyone. Would reduce the cost massively for shipping and production as bitmain would only have to ship boards.
They tend to like to sell products that are fully built. Some have bought chips for projects. That might be your best bet if your wanting a board to do all this stuff DIY.
I don't see them selling boards where you make your own enclosures though. I see them focusing on finished products for the most part. They also make the most money this way.