I think the commodities section of the intel tab can be really useful, especially because it displays all the prices on a map.
Using this, I've once bought in tons of supplies from Jangala at 20 credits each, then sold them at Mimir Siphon Platform each at an incredible 300 CR, instantly giving me enough to double the size of my fleet.
The one thing I did wrong was that I used black market at both stations, hegemony was fine (still cooperative), but tri-tach now has me on inhospitable and I can't trade with them, otherwise I could've exploited this a few times more.
My advice is that if you start off at Jangala, try to earn some credits by trading with pirates first. In so many of my SS+ playthroughs I started off blasting pirate fleets, which only got me like 300 CR per fight and eventually I would supply starve to death. Then I realized how exploiting the trade disruption event in Barad A/B and Jangala can be much more rewarding.