Not sure, but I would imagine it's less than you'd think. The spaceplane was originally a NASA project that DoD picked up after most development was done, and

Not sure, but I would imagine it's less than you'd think. The spaceplane was originally a NASA project that DoD picked up after most development was done, and it launches from commercial rockets (eg they've used SpaceX rockets to launch these before). I would assume that the payload (experimental sensors and components, most likely) are more expensive than the amortized-per-mission cost of the vehicle.