How much you get depends on what you scan. Most things like stars, rocky moons, iceballs, are mostly worthless, a few thousand creits at most. For the big bucks, you want the desirable planets: Earthlikes, terraformables and Ammonia Worlds are worth at least a million credits each, maybe up to 3 million, when fully scanned and mapped. You can increase your chances of finding high-quality planets by filtering out low-quality stars like M-class red dwarfs. First Discovery bonuses are also significant, if you go exploring out beyond the famous tourist routes (and yes, the Formidine Rift is a major tourist route, already well-explored).
I've just sold the data for 25 star systems, most of them with at least one Earth-like in it. Each system was worth over 1 million credits. All but a couple of them were first discoveries. Total for those 25 systems: 120 million credits. I still have another 77 pages of scan data onboard, at an average of about 20 million credits per page. (one "page" equals 50 star systems)
I've just sold the data for 25 star systems, most of them with at least one Earth-like in it. Each system was worth over 1 million credits. All but a couple of them were first discoveries. Total for those 25 systems: 120 million credits. I still have another 77 pages of scan data onboard, at an average of about 20 million credits per page. (one "page" equals 50 star systems)
