Since April first I have built several 6 GPU rigs that mine ETH at 120 MH/s using power efficient (1100 watts total draw) R9-380's. Total cost per rig was just under $1700, including the custom frames & USB risers, labor is about 2 hours per rig at this point for everything, and I can build one in under an hour now. I've sold two on Ebay so far at $2700 + shipping each. I spent another $500 on shelves and cooling, as I needed big barrel fans and a sun awning outside my garage door. to keep the afternoon sun off the power supplies and to push the heat out and keep the rain out.
Formula = Build rig, burn in and test (mining ETH) sell rig = instant ROI, build another rig. I still have 4 custom rig frames in my garage and have also sold a couple of them on ebay as Kada clones that I can build for half of what Mintcell charges.
I actually prefer gpu mining over asic mining.
Of course you need a coin that turns profit and so far eth coin is doing this.
Gpu rigs need more baby sitting then asics but I have high power costs and only Eth coins turn a very good profit at my power costs. I have the solar array joint venture with buysolar and that is all ASIC since it is pretty much maintaince free.
The gpu rigs need to be checked two times a day and two of mine seem to crash 1 time a day.
The other two work about six to eight days then crash.
Why do I have four rigs all with just two cards? All of these will be sold to people I know.
I did this with all my btc gpu rigs.
The day a rig pays for itself mining I sell it to a friend at 1/2 price.
So a 1000 dollar rig makes about 500 profit.
The rigs have
two r9 390 gpus
A 500 gb sss
A corsair carbide case
A DVD- burner
A quality psu seasonic 850 gold (got a good deal)
Windows 7 pro with upgrade to 10 option
Quality mobos
Good cpus i5 6500t or i5 6600k
It is about a 1500 usd build,but I get a lot of vendor discounts and can do the build for 1000-1100