This is a very high power density application that requires special attention to the thermal properties of the boards and where the chips mount. Specifically, the need for very thick power planes and a dense pattern of thermal vias under each of the chips to pull heat away from them and transfer it to the backside heat sinks.
May I refer you to part of the results from forensics I did for AMT back in 2014 regarding why their hash boards were literally going up in flames https://bitcointalksearch.org/topic/m.7610684
The chips are running in parallel to one another, if the temperature on any of the chips goes above 85C (185F), the chip stops functioning until its cooled back down to around 60C (140F) by the continuously running fans which ramp up upon a surge in temperature.
Now even though the thermals are well managed by software alone, i am sure manufacturing the PCB would require some specific things to be taken care of but, then again, thats where my knowledge of PCBs end and thats exactly what i need help with.
My point by the above statement was assuming that if we have a properly cloned PCB, slapping on the components isnt really too hard of a task.
Now as for the cost of cloning the pcb correctly and also the claims of alibaba sellers saying they are able to clone any pcbs for cheap if you ship one to them, i am in the dark.
But what i do know for sure, and i am sure you'd agree, is that its still not going to cost anywhere close to $10k.