Those numbers seem way off. For example, Bitfury chips get around 2GH/s and they probably get ~4k dies out of a single wafer. Your cost for a fully processed wafer is also low, though not enough to even out with being possibly 20x on the number of chips.
Cost should be a lot lower than $2/GH/s at the board level to have chance of being competitive though. Cointerra is selling May delivery units in a chassis with cooling, controller and power supplies for $3/GH/s, and that's including markup to cover overhead. Cost for a 55nm product with chips shipping even in Q2 will have to be way below $1GH/s at the board level to be sensible.
Right, should have thought longer about that. I don't have any access to the latest reports behind paywalls, or needing industry membership, I was seeing 2 year old projections showing 55nm dropping below $1000 a wafer and figuring UMC being the cheapest in the business.
Also, yah, should have thought twice about number per wafer, think it was GPU cores, which can be massive, BFL got 1000 per wafer didn't they on 65, for 4gh chips so don't know what I was thinking there.