This is a try it. Go to any planet and actually look at the build list. At the bottom of the list you will see Items with a 0 after them. Click on the appropiate item so that it will show up in the build box. It will show with a build time of N/A. I found out that if you chose economics the your money flow will increase. It is probably the same with the other ones according to what you have the majority of on the planet.