Lamington Road has few good shops like PrimaABGB, MacIT, etc. Price difference won't be much. However, you may try your luck in saving few hundred bucks if time permits.
ANTEC POWER SUPPLY EDG750 EC edge series /Tier-2 / 5 yr warranty
Seasonic X 850 /Tier-1 / 7 yr warranty/ Rs.12000
Seasonic X 750 /Tier-1 / 7 yr warranty/ Rs.10600
EVGA Supernova 750G2 /Tier-1 / 10 yr warranty/
EVGA Supernova 850G2 /Tier-1 / 10 yr warranty/