Increase the number of ships that are only available in a certain faction's space. For example, the centurion is an old Itani design and should therefore only be purchasable in Irani space and a few select neutral factions such as Orion. Likewise, the vulture is an old Servo design and should be treated similarly. The warthog could be UIT's small fighter as it is more suited to UITs historical role. Some ships like the atlas and revenant are common and widespread enough to be purchased anywhere. I am of the opinion that this would give more flavor to the universe and make things on the whole more interesting. The base models of these ships would be purchasable at neutral standing with subsequent variations requiring progressively higher standing, much as it is now. Grey only factions would likely have all three types for sale, it is after all very space.

+1

I'd like to say lol wut, but +1