It's worth mentioning that I enjoyed Spacetrader. It is a simple space trading game that doesn't take itself too seriously. Buy low, sell high. No need to memorize prices all that much.
The schtick is that it is built off the free version of the Quake 3 engine. So you explore space ports in 3D, finding occasional hidden traders and collecting cargo that is just scattered around everywhere. Bounty hunter missions are plentiful and pit you against hoards of thugs and a boss thug with Quake 3 style blasting, only without the cooler weaponry, sadly.
For $5, it should be some good, stupid fun. Of course, the entire Meridian4 lineup seems to count as good, stupid fun.