[Suicide Junkie]

I like the system I made for gritecon.

Using required mounts and maintenance modifiers on the hulls, the build cost is made to rise FASTER than the size of the hull. Maintenance is made to rise SLOWER, taking into account the higher cost of the components.

In Gritecon, build cost is equal to size cubed.
So an 800kt ship takes the same amount of time to build as eight 400kt ships.
However, that 800kt ship costs about the same as a single 400kt ship.

Big ships are thusly great to have around, but they're really hard to make.
Overall, you've gotta find a balance. If you are at peace, or winning with relatively few losses, then you build bigger ships so that you can increase your tonnage-in-the field without paying more maintenance. If you start losing, then you can build smaller ships, and get more tonnage per turn to throw into the meat grinder.