Registered: Jan 2018
Location: In between parallel universes
Episode IV made it seem like the kinds of things which sell in this galaxy were all electronic, so I imagine some sort of droid machinery, or some common piece of technology which can be fitted into anything. A.I. systems and the like. Although when Episode V opened up the world a bit, planet specific things, like something you'd only find on a very speific type of place entered the possibility of consideration. Really, the best place to look for what you'd find in the star wars universe is in the old marvel comics, or in the Holiday Special.
In the prequel era, you'd probably be able to find more things like different types of plants and insects from different areas. I don't know. I want to say something, but my brain just isn't working right now. Kybercrystals, metals from all over the galaxy, etc.