So, miner manufacturers are making their most efficient miners unavailable except as bare ICs with which to design and build one's own miner or available as a 'buy a share of my farm running these efficient ASICs.'

Like Bitmain.  Many of us expected to buy an S5 post-Chinese New Year.  _Not available_, _Sold_Out_.  Now I'm wondering if it would be worth it at all!  I'm at a state of cashing in my mined bitcoins to pay the electric bill.  Profit is a slim margin helped by the non-burning of propane for heat this last winter.   Now I'm wondering if payoff of a new miner, after deducting electric costs and taxes, can ever be achieved!  Bitmain still offers C1's for sale but my C1 uses more power than I'd like.