Great suggestion, seems logical too. When looking at astronomy in our own solar system. We know the planets are there because that information is globally shared. The same with other discoveries made in the universe. Plus we're sending probes to learn more about the planets in our solar system. All that is shared information.
So in ED a system wide scan (aka honking) would discover all solar bodies and asteroid belts in the system. The FSS gives you the optional task of getting detailed information of the planetary body. When someone sells data unknown to the galactic DB it should be updated and everyone who loads an instance of that system afterwards should see that data. Weather it be the results of a fast system scan or additional detailed planetary scans. All game clients get the information from the same galactic DB. So any game client who instantiates a system gets the data that is in the galactic DB at that moment. So it could be you're discovering something in the system and someone else is just selling data for it, which you don't know about yet.
Although you lose systems where not all planetary bodies are discovered if the honk would return as it was. Also the fact of selling the data. I think it's not logical that the maintainers of the universal cartographics would pay twice for the same data. Even when at a reduced price. There are more than enough undiscovered systems, so you should only get paid for actual new discoveries imo. For example the road to riches. Why continue to pay for data that's already owned by universal cartographics. It makes no sense. Even if two commanders sell data at the exact same time, only one will get credited for it in my case scenario. Mutual exclusion in the form of an atomic operation. Only it would come as a big surprise to the commander who ends up second place though. Since both see that they can sell the data. Maybe that and what I mentioned earlier made them think otherwise. But I still think it makes no sense.
Why the need for an additional module though? Both things can be done with the internal discovery scanner. Buying system data. Don't understand why this is in the game at all. It makes sense that UC is funded by different factions. So why the virtual micro transactions? We already do the heavy lifting for them in terms of missions. We're probably severely underpaid