One of my favorite games for the tablet is Galaxy on Fire 2. It fulfills my Star Wars fantasies from youth because you can fly around the galaxy, fight pirates and aliens in space, buy and sell commodities, and complete pretty fun missions.
If you are looking to make money to buy a better ship or better weapons, trading commodities is an easy and relatively violence-free way of doing so. You will need decent capital and a decent amount of cargo space on your ship before it becomes profitable. It would be hard to earn money starting with less than $200,000 in capital and less than 100t of cargo space aboard your ship.
Here is a google table containing all the commodity prices, best, worst, and the profit margin / price difference of trading.
I made this spreadsheet by buying one of every commodity that I could find and then copying it out “Hangar” view. This is for GoF2 on Android and probably doesn’t apply to the original GoF.
When time permits, I hope to write a greedy algorithm that goes through the price lists and systems list and calculates the most profitable and most optimal trading route :)