Droid parts tend to be rare overall in the game. They also tend to sell slowly. For a Cybertech, there are a lot of other things you can make that will sell quickly and droid parts are excellent for RE'ing and getting Augment Parts to sell. Due to these reasons, you are likely not going to see many on the GTN.
Some missions will give you modifiable droid parts for T7. Try using those and Planetary Commendation mods to gear him.
I have to agree with this, nobody are buying my crafted droid part on the GTN, Are you by any chance playing on the Harbinger? I'll craft some droid parts for you.