@aaron3719 my test rig is 2x 1060s, I also have a 970 running.
but this is irrelevant, if you run the numbers out in an actual spread sheet, and actually include all the parts, fixings, cables, power, shelving, etc etc.
Priced out a full rig with 1080 TI units, with the same results. My calculations were based on a 460 per unit price of zcash (at the time of building the sheet) My only other thought is cost of equipment is too high for me.
If you have other numbers please share. I would be happy to share my spread sheet.