This suggestion is from a dream I had recently (yes, I dreamt about Freelancer, I know I have a problem...) I've not really thought it through so see what you think...
How about having some unique items in the mod? Without being unbalancing, wouldn't it be cool to have a special shield, or thruster, or gun, that absolutely no-one else has? These could be 'seeded' into the mod at random to active characters (like a lottery) to either use or sell. They would be totally in the domain of players, and not sold at bases, dropped by npcs or found on wrecks.
Admins could make periodic checks to see whether the items still exist and are active, and if they're not, simply introduce them again. They could easily be given selling prices at bases, but these prices could be small or zero to discourage players from selling them.
Role-played characters:
daedalus - Liberty Navy
bandersnatch - Ruthless criminal possessed by a (huge) alien
Shredder - Small-time Kusari pirate, looking to join the Blood Dragons
"Bounty Hunters. We don't need that scum." - Admiral Piett