Here is an idea lets have trade goods/luxury items. Trade goods would be very valuable credit wise but more or less useless to you (like gold or furs). Luxury goods could have a very high mood improvement if consumed or use i.e. like spices or even drugs. Some such goods you could produce or collect other require research but most would require a source on the map i.e. a gold vein or a spice bush/plants. You might have to process some of these and they would be a serious investment in terms of materials and people but offer substantial rewards for selling them.