The Galactic Junkers

There is 8 ship in total (need to buy 7) and you need to buy them all on the same file.
I suggest you to make a save before buying everything to not loose your credits. (You loose the previous ship you have if you buy a new one.)

To buy ship, just go to any station and talk to the Ship Merchant. The ship to buy is in the third window.

There is 3 ship that cost less than what it is writing in game.

Walrus= 5K -> 4.5K
Turtle= 4.5K (Base, don't need to buy)
Caterpillar= 4K -> 3.5K
Swordfish= 6K
Viper= 5.5K
Orca=6K
Goliath= 7K
Oarfish= 2K -> 1.6K
Total Needed=34.1K

To get 34.1K you will have to limit your purchase to the cloacking, the engine, the shield and the strongest gun that cost 850 credits.

The main way to get the credits is by selling the drop of the asteroids and in the station.