I just noticed that eco-starbases also boost the "base" value of a trade route. I'd personally given up on building freighters unless i was losing, because trade overall seemed very very marginal. (esp compared to GC1) I had even tried using Korx with heavy trade bonuses, and it just didn't work.
However by building eco- starbases at the other side of the route, maxing out thier trade bonus, and THEN establishing the trade route you can actually make some dough...
Is this common knowledge ? The manual, laugh, only says they boost the freighters value while in the starbases zone.
And don't bother with the galatic baazar it doesn't affect this sort of trade...