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 .
Best bet is to either roll a toon to be Cybertech to make them yourself, or find someone (in your Guild is the best bet) who has a Cybertech toon and ask them to craft them for you, if doing the quest reward route doesn't work for you.
Alternative is to buy them with Planetary Comms from the planet equipment vendors.
There are many parts you can buy and craft that take mods just like an Orange shell would; you could also keep the gear up to date using normal armor mods stuck into the moddable droid parts.