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.