Pssssh. Here's three good ones:
1) Alien Organisms from Freeport 9 to California Minor. Do it in the Humpback and you make 475,000. (Unfortunately, about 20 of the organisms degrade to the high perishability of the commodity, so expect to make around 435,000 instead.) From there, fill up on Water and bring it back to Freeport 9 for a profit of 54,000. Repeat as necessary.
3) Go to the Malvinas Field in Tau-37. Every single rock you blow up contains Niobium. Load up and sell it at Leipzig in Dresden for 1,600 per. It's easy to make huge profits this way; just watch out for the Outcast patrols in Sabers.
2) Get a high-level ship and camp outside Rochester in the New York system (directly above Manhattan on the map). Every so often (at about 5 minute intervals), a CSV will come out, carrying 79999 of some commodity. Blow it to hell, and tractor in its loot. Of course, kill any ships that attack you and take out Rochester's turrets for safety. At high levels, the Rogues and Junkers there pose no threat at all. Commodities you can pick up here are things like Diamonds, Niobium, Artifacts, Scrap Metal, Consumer Goods, Water, HFuel, and most importantly, Cardamine. IF you're lucky enough to get a Cardamine-carrying CSV in your sights, shoot it and take the Xardamine back to Manhattan. Sell it for outrageous profits.
Well, I hope you found these helpful!
If it's not the Cardamine that's talking, it's the Synth Paste™.