We have played with several options for building Starbases.
In early builds the player would build a starbase from a planets production queue, this tended to slow the players ability to both build up their worlds, and build up their Starports. In short it was not fun and slowed down the game.
We also considered having starbase create their own production, by mining systems, asteroids etc. This quickly became too complicated, and you ended up treating each starbase like a planet, which got out of control fast.
We went back to a modified version of the GC2 model of using constructors, because in short it felt more fun. The primary difference is that in GC2 you can make constructors, with multiple modules, so you can send over a ship that will let you build 3 modules in one push, or even more late game. Hopefully this will cut down on the constructor spam, yet still let players do some of the more fun tactics, like quickly rushing up a Military base on you border, when a war starts.
That said we will be polishing this up as the betas continue, and the governors screen and rally points, which will be coming in beta 2, should make the monument of these constructors, starbases, and ship yards, much simpler.