What supplements would you like for Colonial Troopers?

Free Traders - trade rules. A hoary old trope of the genre, I suppose.

My first preference would be for something similar to the old Elite game, which as I recall had a more explicit connection between the riskiness of the market and potential profit than, for example, Traveller in any iteration I am familiar with. This would be helpful for encouraging risk-taking behaviour on the part of the players.