Of course no system will produce that behavior. That's the point.
My point is that its just another black box algorithm that you want to use to generate some values that could be generated in much simpler ways.
Its just abstracted at a different level.
Yah I agree it's a fudge.
I don't think it's overcomplicated! I think it's the most basic set of rules to automatically set the prices of an arbitrary supply chain.
I can't think of an alternative that would be simpler, can you?
Then there's a question of how often you update prices. If you don't do it with every unit of something sold by the player, you could have a situation where the player can buy/sell the same stack to the same planet over and over, with profit (costs X: players buys, there's less "current supply", it costs >X, player sells, repeat). That's not particularly hard to avoid (most likely with "hacks", whose effect on the overall economy may not be immediately apparent).
You brought up some interesting points, a few I had thought on already (a few more I had not!) but I couldn't voice any concern as I do not know exactly what your aims are with this game (I only know that right now it's an interesting hybridization of star control and mechwarrior, which was easily worth my 10 bucks)
About the devious player: If a station sells to the point of creating a demand for supply, then the cost associated with that should be passed to the player through the sale. Selling by unit rather than by batch is a simple way to approximate this. (I suspect the formula would be rather complicated though)
However, you are absolutely right to say that if this results in exponential fudging, it will only cause more problems. I believe it can be avoided. It's hard to say what other kind of things might crop up though!
preferably i want something a bit more complex than X3. but not so complicated as EVE. at the very least i dont think items in game should have hard set max/min prices but instead prices dictated by a more complex algorithm than X3 where if a station has 50% of its max resources the demand price is 50% of said resources min/max price scale.
You and me are on the same page.