Hi Naveen,
I am not sure about the Indian custom duty as I work here in Singapore and have not yet taken back hi-fi stuff to India. I plan to buy HT stuff here before I move back to B'bay/Pune as the price difference, for HT stuff, is quite high between India & Singapore. Its not only the AV receivers, but the speakers are also much much cheaper here. A pair of B&W 685 in SG is $980 (Rs 26,000/-) while the same speakers in India are for RS45,000/-.
A good place to buy HT stuff is "The Adelphi" building near City Hall MRT (Opp Funan IT Mall). You can try out KEC sound (
HIFI BARGAIN | Kec Sound Pte Ltd), Alpha Audio as I know these are reliable shops due to my previous dealings with them. You will be able to find most of the brands (speakers, amps, transports, A/V receivers, cables) in Adelphi. Yesterday, helped a friend buy a Marantz 4001 with a pair of Mission 34i, pair of M30i & a M3c2i for $2050 (Rs 55K) with a Marantz iPod dock, speaker wires, delivery & installation thrown in free from Alpha Audio.
If you go to these shops, you should bargain on the quoted price. The more stuff u buy from a shop, the better price you will get.
If you are not a permanent resident or a citizen of Singapore, you will get 7% of the cost back as GST (goods & service tax) refund. So it makes the deal more sweeter for visitors

. Make sure you ask for the GST refund forms at these shops.
Feel free to ask me any queries you have.
Ajit.