You probably won't see them much until you reach a middlin' level. They start showing up as drops from enemies or in containers.
One trick with vendors is to save before talking to them. If they don't have what you are looking for, reload and try again. It's not guaranteed you'll get what you want but sometimes it works. Also, don't buy the cheap licenses. They only increase your odds of getting crappy weapons and armor from your guy in the Mako bay.
Jim