I have found a good reliable way to make alot of money pretty fast (without hacks/edits), and I though I'd share it. The whole reason I spent the time to do this, is that I really wanted a space station, but couldn't afford in in a million years through my usual methods.
First off, proceed through the story line as quick as possible untill you have the laser ship.
Then, assemble a good fleet to go with your laser ship (I used all tigers)
Next, find a moon that has a High Wealth/Population rating, 7/5 or above is good, and has a low military rating 1 or 2. (it is also nice if it pays well for at least one of your goods)
Now attack this moon over and over again, as your ships need repaired, just have them repaired on the moon you're attacking...
Eventually you will have something like 3000 weapons, 2500 slaves and 4000 goods to sell (if you haven't sold them already). and you should have been able to keep your ships repaired this whole time with just the cash you get from the battles.
Sell everything off, you should get around 74000 gold for this if you did it long enough.
Now go assault Venus to get your spacestation, now land on Venus and repair everything.
Replace ships in your fleet at this point if needed, and have fun beating up other planets with your new spacestation I recommend hitting Earth a time or two as it has very high wealth/population and low military.