I might be mistaken, I've never gotten into the whole space/sea/otherwise trading genre, but DarkStar One might be worth a shot if you're really hungry for it.
Haven't played it all that much, there's a plotline involving you making your way across the galaxy (at first anyway) but there do seem to be ample opportunity to go bounty hunting, helping the law out, trading and such. gog even has it in their catalog though it does go on sale on other sites as well too. Personally I got it in an Ascaron package which contained Port Royal 2, Darkstar one and Sacred gold for $2 so worth looking around.
Also I seem to recall something about a game called Hardware, which if I recall branded itself as a sort of MMO of that kind of game, set in small societies in craters on a planet. Having humans as pirates or bounty hunters (if you played pirate) and such might add a bit, but no clue how it works.
Also there's a Free to play MMO out there I've been peeking at called Black Prophecy. Not sure if it's released yet. Looks like a sort of take on Freespace, but knowing MMO games it'll likely contain some trading and such too.
Again, apart from DarkStar One I haven't played any of these, but they're what I recall being intrigued by off the top of my head.
sturryz: any others?, i hunger for games
Also....are you related to Sinistar?
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