Franco,
Trade in GCIII is well sought-after. If you just go a to the 2nd tier into the trade techs and are able to have at least 3 trade ships you will see a return. The most important thing to remember is....time.
The trade route value increases over time. So the initial trade route is 6 credits. PUNY. However with a bit of research and time those routes can jump to 47-86 per route.
Also if you go up the traders line in Pragmatic and can manage to get them converted to 'luxury' routes they practically double in value. They also dramatically help in UP votes and diplomacy. Trade is KING here.
Obviously I am a trade advocate. Most of the benefits are not fully realized until you unlock some "Trader pragmatic traits".