Sales tax has nothing to do with mining.
If you are only worried about power cost then for a large farm you are doing it wrong.
If you can move into an empty DC or factory or other facility that already has all or at least most of the power / cooling / infrastructure you are already there.
Because doing it properly can cost 10s of millions and take months.

If you want to do it quick and dirty then yes you can move in just about anywhere with cheap power, then all you have to worry about is the infrastructure failing or not having stable power.

-Dave