Having read a some, but not all of the starbase posts, I am left with a question. If your starbase carries with it a maintenance cost of 5bc / turn, and it only increases trade revenues when a mini freighter is in its sector, how can it be a worthwhile investment?
It seems to me that more often than not, it's just going to be sitting there generating maintenance cost. Even in a sector where multiple trade lines cross, there's still going to be a lot of down time when the sector is devoid of traffic, and thus your starbase does not generate any additional revenues.
However, after some of the patches to GC1, the 5bc/turn maint fee went away. Even if it stayed, the starbase is important for three reasons: extending the range of your ships, harvesting resources, and having benefits (with the higher techs) to your planets.