I looked through all my old business cards, but I could not find the company that supplies hangers to dry cleaning companies and commercial clothing stores. I would ask one of those people where they get their hangers. That's what I did.

As for a recommendation, I would suggest a sturdy wood or plastic jacket hanger for the tunic/coat, I would not necessarily do a suit hanger since I would think you store your tunic and trousers separately, since the likelihood of the same numbers matching the same student is slim.

Hope this helps.