> As of now the cost per block is probably already about 100USD, probably in
> the 50-150USD.

This is wildly at odds with reality. I don't mean to insult, but
please understand that every post you make here consumes the time of
dozens (or, hopefully, hundreds) of people. Every minute you spend
refining your post has a potential return of many minutes for the rest
of the users of the list.

At current difficulty, with a SP30 (one of the
leading-in-power-efficiency) marginal break-even is ~1144.8852 * $/kwh
== $/btc.

At $0.10/kwh each block has an expected cost right now, discounting
all one time hardware costs, close to $3000.