GURPS Traveller offers starship transponders (well in a bit more detail) so there's likely alot of information you can get from someone within active sensor range...if you believe it and if they have theirs turned on.
I'd expect there'd be plenty of chatter from ships in orbit and you should be able to contact the "port net" and get much more details about things dirt-side (or from the space station if there's one in the system).
You might be able to get a sorted list after a query for all ships selling goods and/or headed in a certain direction. Not to mention feedback on ship coming from where you're planning on heading, such as week-old pricing on hog-belly futures, etc, etc.
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