I updated the BOM to reflect our use, currently we have to have six dedicated and three auxilary, making 9 total motor controllers coming in at just over $100 (not including shipping for the boards and parts). I think that this is pretty good because the closest equivalent circuit that I can think of is using four solid state relays per motor which would cost significantly more, and there would still be the same hurdles to overcome. Even with two solid state relays and the transistors it would have been more expensive.