If you're a force user, you can automatically have one. Pretty much any canon tech, as long as it's not ridiculous, OP or Celestial, you can have. Custom stuff can be run through the factory for approval, and custom stuff that already exists just requires that owner or author's permission to use. Some of it can only be acquired IC. Aside from that, go wild. Just don't have ridiculous Force powers or every power in the book because that's not realistic or fair.
EDIT: Also, Cortosis, Songsteel, Beskar, all that sort of stuff has to be acquired IC.