The light-gas gun launch + rocket hybrid is a very interesting concept. It consists of a large, but conventional light-gas gun propelling a g-hardened payload 2/3 of the way to orbital velocity, then the payload uses its own engines to accelerate the rest of the way. The scheme is advertised to cost around $400M, but we should consider that within an order of magnitude. Even at that, the opportinity to significantly lower launch costs should be embraced.
Halving launch costs would be significant, it would save the satellite industry many billions. Note that half orbital speed discount is much more than 50% in launch energy savings.
