Recommended wattage for sli 970 is 700w. Unfortunately, there really aren't any good 700w units, you'll get 650 or 750w for a quality unit.
Cpu OC @200w
Mobo +accessories @100w
970x2 450w (2x pcie =150w, 4x6-pin or 2x8-pin =300w)
Those are rough maximum potential draw, total = 750w. The gpus wont pull that wattage, and most ppl won't see a 200w oc, so a 750w unit will leave plenty of headroom, using 50% to 70% power, which happens to be peak efficiency range.
Considering how important a good strong reliable psu is to the health and safety of your expensive pc, a quality 750w psu is worth the investment. Better that than push your luck with an underpowered unit, no matter what quality of build.
In India you can find Seasonic 750w, Antec HCG 750w, Corsair AX 760w etc, depends on what etailer you use. Also, the CX/CS do not do well in heat, and Indian summers will easily reach 40°C+, which is right at the max tolerance for those units. So unless the pc is kept in a climate controlled area, I'd not suggest either series as viable.
I had a 600w CoolerMaster for a few years in my Dell 8400 pentium 4, which has miserable airflow, and it worked flawlessly, unless I gamed for @ 1 hr, at which point that p4 and gpu would heat the case bad enough to put the psu into thermal shutdowns. My room is 22°-23°C year round. Not a big fan of CoolerMaster psus for gaming purposes.
Corsair CS = CS = VS, all mediocre entry level psu that even corsair states is not recommended for gaming purposes. If you must go with Corsair, look for HX, TXv2, AXi, AX or HXi. The other series are pretty much junk for gaming.