We have an iStore by Reliance in Hyderabad. Not sure if they have it in Chennai but check it out. They have all the latest Apple products, cables, accessories, etc. Only terribly expensive, but at least now we can say we are more or less on par with the rest of the world in terms of Apple products and don't have to depend on getting them from abroad.
Try Mercy Electronics or take a walk though Ritchie Street.
I must warn you, though that iPOD is a little finicky and needs good connections. I have thrown away two 3.5mm to 3.5mm cables (purchased from Mercy) to use my iPOD in my car, and finally settled for a good branded one. A little shake and these other cables end up making scratch noises that are horrible.