Effective from December 01, 2015, India Post has increased postage rates for all foreign bound letters. The official press release and gazette notification is here
. Detailed explanation of revised postage rates is here
I believe that postage rates mentioned above are for unregistered mail (which don't have a tracking code). Registered letters will be more expensive, currently they charge ₹50 extra for registration (If I remember it correctly).
Compared to other countries, our rates are still reasonable IMO...