Most Mk. II military starships, a little too much.
Most Mk. III military starships, way too much.
I have been pushing for reducing higher tier starship knowledge costs for quite some time.
Although think that 2k for Mk II and 4k for Mk. III is too small, I would be content with 3k and 4.5k-5k, respectively.
Keep in mind, there is no Mk. IV starship fabricator, and as such, Mk. III military starships should have a knowledge cost of less than Mk. III fleet ships.