When you get closer to the end of the game, you have to beat a Vortaag Battleship. Easy way to do this, is to buy the ship cost's 1 million credits. You can get this thing with the low price if you try Haggling minigame in Keck's shop. Then better for you to buy some weapon. First of all buy a weapon which compel your enemy's to loose 1 or more move's. Second good weapon is the laser, which shoot with a power for each 2nd of your LVL's. Both weapons is in Vortaag Shop.
To get easy all of this things I create list of planet's with cargo's and shop's:
Auriga| JF174M: Alloys x32; Technology x50
Sagitta| MP109R: Alloys x32; Isotopes x50
Libra| AD329T: Alloys x48; Technology x48
Beta Centaur| PN383X Technology x48; Isotopes x48
BS736Q Gold x48; Contraband x48
|Where to sell?!|
Alloys + Minerals - Vega Station:
55 \ 22
GOLD + Isotopes + Tech + Contraband - Port of Elysia:
65 \115 \ 86 \ 154
It takes about 4,5 hours. Good luck.