I've never been one to use the sensor techs much, but when playing a gigantic map recently I did research the sensor level that allows you to build the Galactic Guidebook. It says that it's supposed to reduce the cost of the survey module to zero, so that you can add it to any ship. After researching the tech and then building the GGB, the survey module still cost money for new ships. Is this a bug, or am I misunderstanding the goal of the GGB?