You may get cheap & unlimited GPRS connection from Airtel, with no GPRS roaming charges within India, but the speed is pretty low.
There is also Reliance communications that provide CDMA modem & connection, but the speed isn't fast as well, and you have to be indian resident to get connection...
You may connect your laptop in most of internet cafe's for high speed internet, and the price is around $1 or less per hour
