So miners are buying prebuilt gaming PCs and then ripping out the AMD graphics cards and reselling them on ebay. Like this one that originally had a RX 480 in it:
http://ebay.to/2eWkqIv
Since this had a 480 in it you can get away with putting any GPU in it which uses the same or less wattage. Like a GTX 1060, which requires 120 watts, same as the RX 480.
You'll want to use a blower cooler on your 1060 since the case on this PC doesn't have much ventilation. You can get a reference cooler GTX 1060 3gb for about $250-275
http://ebay.to/2gFV2dY
$624 for an "almost prebuilt". You give up 1gb of vram from the 480, but at 1080p that is not going make much of a difference, and this is a 1080p gaming PC. For people who don't want to mess with building their PC but think they have enough skill to at least swap out a GPU I think this could be a pretty good way to go.
If you don't care about your fan running at high speed all the time and being kind of loud get this 6gb version.
http://www.ebay.com/itm/zotac-GeForce-gtx-1060-6gb-/272832605632?hash=item3f86172dc0:g:S-YAAOSw9L1ZrIVi