I know how to get it
I know this thread is kinda old, but I know how to get the galaxy droid. For those of you that have seen the random entries where people don't remember exactly what they did, you'll be really happy. I have exact instructions. I don't have much time now, so i'm only going to give you the instructions, i'll tell you what changes when I have more time, but I will say, don't use the galaxy droid to travel to anywhere but yavin, tatooine, kashyyyk, manaan, and korriban. And make sure you follow the instructions exactly, not being bossy, but this is a very specific glitch.
1) After you've got the fourth star map, dantooine and 3 others, I did T, Ka, and M, SAVE YOUR GAME!, and select dantooine as your destination. You get captured by the leviathan. Play the leviathan through normally.
2) After you leave the leviathan and you've had the big long discussion about you being [SPOILER!!], you'll see a sequence of you landing on dantooine.
3) You'll really be on the planet that you haven't got the star map on yet.
4) SAVE THE GAME!!
5) Exit the ebon hawk, walk around the landing pad a bit until ziagrom (a green twilek) comes up to you, and then re-enter. This could freeze. If it does, re load from save game on instruction number 4.
6) Go to the galaxy map, and select yavin, if you're on the xbox, and have no xbox live, it may not work because you have to choose tatooine.
7) You'll get attacked by sith fighters, defeat them.
8) There may or may not be a landing sequence
9) All your party members will be in the centre of the ebon hawk, the galaxy droid should be in the cockpit, and swoop droid in garage. The map should be either of the leviathan bridge, command deck, or of manaan underwater base. Zallbar follows you around, DO NOT CHANGE YOUR PARTY! SAVE YOUR GAME! You now have a permanant galaxy droid save, BACK IT UP ONTO EVERY MEMORY CARD YOU HAVE!
10) Go to wherever I said you could go before, if you go somewhere else, this game, is over. Too dramatic?
11) This may well wreck your game, it's meant for you to have a bit of fun, then reload from the save game from instruction 1, then do it normally.