Mumbai’s two airports are 30 km north of the city centre. The journey to the city centre takes about one hour at Rp 300 (€ 6). And 30% more between midnight and 5 am. This was the price in 2006.
Chattrapathi Shivaji International Airport handles all international flights and is 4 km from the domestic airport. A free shuttle service connects the two airports.
Domestic flights of Air India depart from the International Airport.
Some domestic carriers:
http://www.airdeccan.net/airdeccan/home.asp
http://www.flykingfisher.com/
http://www.airsahara.net
http://goair.in
More info about domestic airlines:
http://www.indiatravelite.com/airway/domestic1.htm
More info about airports worldwide:
http://www.airlinequality.com/index.htm