I'm not familiar with any of those games you mentioned, but how about
Naev?[0] It's actually in a very incomplete state and in desperate need of
some love (for the best experience, stick to the Empire; lots of dead-ends
exist with everyone else), but it's a game that sort of comes to mind when
you say "space trading game" (it's more mission-oriented and most missions
are delivering cargo, but anyway...)
Another one that looks interesting to me at least, though it's 3-D, is
Pioneer.[1] This one seems to be in active development, unlike Naev (most
recent release was in August).
[0] http://blog.naev.org/
[1] http://pioneerspacesim.net/