Hydrogen, which is used in the propellant, is considered the most efficient fuel. But to use huge quantities of the substance it has to be maintained as a liquid, for which very low temperatures are required. For this a cryogenic engine is crucial because it is designed to handle fuels at low temperatures. Analysts say a fast-growing demand for communications satellites would make the GSLV very useful. India has in the past relied heavily on Europe's Arianespace to launch its satellites.
Japanese costs are even higher.
With time, the costs could come down further. Welcome to the Universe.