The easiest way to fix what some see as a broken economy here on STO, would be to put a percentage limit on all of the items allowed to be sold in the exchange or to vendors.
They could even put a sliding percentage scale in place based on what color the item is.
The higher the in-game value the lower the allowed profit percentage.
So if the item is Common, perhaps 95% to 100% profit would be allowed.
(Unless of course, you sold the item to a Ferengi. Then the profit margin would be in the Ferengi's favor. This could also lead to some very valuable items only being available from Ferengi's. They would of course charge exorbitant prices and tag the item with a 'Bound-On-Pick-Up nerf, thus keeping Their profit margins high... as it should be.)
If the item were Purple there would only be allowed a 10% to 15% profit.
And everything else somewhere in between.
Obviously this would not do anything for exploitable 'bugs' that might pop up occasionally but it would bring the runaway price-gouging economy back in line to what the developers probably had in mind when they created the game.
I like playing this game for the value of being able to immerse myself (kinda-sorta) into the world of Star Trek... I have never really understood what it is that some folks see in making tons of 'FAKE' Star Trek money.