I've been attempting to play as a trader in my last few games and noticed that often there were very few deficits / high demand for goods. Often the spread between the best sell price and best buy price was very small for most goods. Small enough that even purchasing and selling on the black market would not be worthwhile. I took this to mean that trading wasn't meant to be very lucrative.
For awhile now I have run numerous mods that add factions and I have been enjoying the added variety and activity provided by these mods. However, in my current game I flew around to a number of the planets added by these mods and noticed that they were all prosperous, secure, and had an excess in production with no unmet needs for goods.
I wonder now if the faction mods I have been using have essentially provided too much production of goods and not enough demand. This may be causing the lack of goods deficits and the small spread between buy and sell prices. I am not sure however, was wondering what other player's experiences were with the economy and faction mods.