There is a pre-paid taxi service operating from the airport;
Extracted from Frommers Should you need to hire a taxi, make use of the overpriced but reliable prepaid taxi service; a trip to a city-center hotel should cost Rs 400 to Rs 500 ($8.75-$11) but may depend on the amount of luggage you're carrying. (Expect to pay well over double these rates for a hotel airport transfer.)