Looking at the prices and depending n where you live you could probably get a 4gpu rig $700 for the Mobo ram cpu psu and HDD and the rest for the cards.
How much should I spend on a power supply? I am building a rig with 6 1070s and was thinking of buying a EVGA SuperNOVA 1600 P2 80+ PLATINUM. Any advice is appreciated.
Can't go wrong with those - they are pricey but those and G2 850's are my 2 top favorite PSU's. I also have Thermaltake 1500, Quark 850's and Corsair 850's, all of them have been hashing away for the past year no issues so far but who knows down the line.
That is why overkill unless you plan on adding more gpus into the 6 you rig. A 1200w platinum PSU is good. Evga or cosair.