I can remember in the animated series, Orginal and in TNG that there were regeneration/ healing drugs.  Or a training that did that as well.  That idea was used at least once in all the Star Trek Series.  There were differnt names used.  Remeber that Bones gave Kirk Tri-ox.  So he could continue to fight Spock in the Kali-fe. Garth of Izar had his special morphing training. That could be someting.  Some sort of Spy ability trade, by the morphing ability or the hire of someone like the Suliban's.  I went through my books last night looking for stuff.  But most of it is like Spikan Flame Gems, Romulan Ale, Klingon Blood Wine, Tribbles,.....there was a creature called a Glomar....was the natural predator of the tribbles to keep them under control.  Klingon's wanted them bad and made pets of them (animated).  I was thinking of the Doctor from Voyager.  Could independent holographic personel be used as a trade good?  Many of the things in Star Trek like Androids, Super Computers and the like.  Can already be simulated in the tech tree.  What about exotic pets or plants for a moral boost?