It's never actually specified what he has in stock, just that he has an entire storage dimension. In the show, he pretty much had anything he could need for the situation at hand, and I understand that wouldn't work for game mechanics at all. Should I just list the items he's been shown selling/using, as well as the most probable Elite Guard thefts? Or leave it more open and run specific items by you guys as needed?

Or the transwarp could always be faulty and not allow access to everything. That's another option too.