Well, I have somewhat balanced the commodity system. Basically, commodities regenerate at a (slow) rate so that you can't really trade between sites that often. And each site only wants a certain number of any given commodity. It's not a bad system, if I tweak price margins it should be fine.
There is a fairly well-known problem in game design theory. That is, if you give the player multiple ways to accomplish the same goal, they will tend on the whole to choose the most efficient one. So it becomes difficult to give the player meaningful choices. Think back to your favorite (or not-so-favorite) RPG; generally, towards the end, you only use a few fairly refined battle strategies (e.g., offering + genji glove + dual atma, or economizer + magic box + ultima + quick). That's what this is all about. You have 50 spells in your inventory, but once you find one that works well, or works better than most, you use that one.
Argh, I normally would rather not rant on game design "theory" but the reason I am is because vex has many repeatable, effective strategies. Moreso in that I can't really hope to prevent every exploit, i.e., I can balance things fairly well but the idea is I really /do/ want a big world that /isn't/ too carefully designed. How do we manage this from becoming a game where the player only has to do one thing, and do it a lot (whereupon they become very, very bored)?
The answer is the timeout system (or at least, I hope it will turn out to be an answer). What happens when you do some action that helps you "grow" (in the RPG sense) is there is a timeout counter of some kind. So for instance, shooting monsters on a planet will gradually depopulate the planet. Those monsters /will/ regenerate, but only over time. So in general, the player is discouraged from sitting around in one place shooting monsters because, after a time, there won't be any monsters to shoot. Most players will recognize that there is a "growth per time" factor involved and move somewhere else. Sounds like a MMORPG already doesn't it? Ah well...
Or for instance, suppose you buy/sell commodities. You may find a single route that earns you good money. But you may end up working other routes, shooting monsters, stealing, etc. in order to earn enough money for that new ship or weapon or what have you, simply becuase at any given play session, you can only actually work that route ONCE.
The idea then becomes to try and make the "per time" resources scarce enough, and the requirements for advancement steep enough, that when the player wants for instance to buy a new ship, he/she will be forced to do a number of different things to earn enough money/exp or what have you.