Depending on the budget u will get 12AWG wire at Cables & Wires @ Lamington road for 30/50 Rs per meter, little better Designer Audio at Tardeo and after that any of the mumbai dealers like AVI,Lakoxy,Boomerang etc etc will offer u 12 AWG from the cables they endorse.So depending on ur budget u will get a cable for 30/- to about 2000/- rupees per meter.
I echo Dinyaar's suggestions ! He's 100% right and you should go for the one based on your budget !!
However I have one small addition to the list !! its MX,they have some decent cables at affordable prices so check that out aswell ! Usaully they are available in almost all the shops in LT road ! so thats the place to look for this cable !
Once in LT Road please be beware of the Great looking and even more greatly priced ones !! they are only great looking and very very bad in actual quality !! so stay as far away as possible from them !!