So I found a good way to make easy fast money through space station trading. Firstly, free up at least 6 inventory slots in your exosuit... more is better obviously, but 6 should be minimum. I did this with 8 free slots. There will be variations station to station but the basic formula is constant and it goes a little bit like this.
Head to a space station and look on the station's trade hub module under the SELL option for single inventory space items with a STAR next to them. You want something like Dynamic Resonators or Korvax Convergence Cubes, really anything that has a high dollar per item, but these 2 items worked out best for me.
Example:
Dynamic Res. - 55,932.2 per unit, +103.4% (galactic avg.)
Korvax Con. Cube - 55,570.9 per unit, +102.1% (Galactic avg.)
(note: You will BUY these items for around 33K a piece and re-sell for over 20K a piece profit.)
So what you would do is head down to the ship bay and buy up these items from the ships that drop in randomly. Be sure when you BUY from them that the item is NOT starred in their inventory. It's ok if the galactic average is in the red and showing something like -2.1% or whatever, you are still buying it at something like 33K per unit and re-selling it to the trade network terminal at more than 20K per item profit.
If the trade module inside the station has nothing starred with high per item cost you can apply this exact same thing to the trader ships and omit the station strade hub entirely. Just start looking over all the random traders inventory as they come into the station. Look under the SELL option to see who buys high dollar items with a star next to it. You will quickly realize the traders are anything but random as often the same named trader will be inside the station, docked, with 2 or more of his clones. There will be something like 5 or 6 differently named traders all with different items they will pay big money for (starred items). All you need to do is remember that traders name (your SELL to guy) and buy up all these items from the other traders who come in. Each named trader has the exact same prices, like all the guys named "Bozan" all are the same, all the guys named "Relyelli" will all be the same etc.... keep this in mind.
In an hours time I made several millions of units. Now, keep in mind some stations are A LOT more work than others to get the buy low, re-sell high cash flow going steady. Especially if your SELL to guy is really random and infrequent. Just head to another station and try there. I think it took me like 2 stations to finally find one where ideally I would be able to make the inside trade hub my SELL to guy. This makes it super easy to offload your full inventory after buying up everything from the ships and not having to wait for a certain guy to sell to. I can just jetpack up to the door sprint inside, sell everything for a massive profit and be back out on the dock in under a minute.
Happy trading!