I've been toying with this, but haven't found OTC sources yet. I think they exist, but I haven't seen em:
A more effcient way to make HBr might be to brominate tetralin (tetrahydronaphthalene) instead of naphthalene. In my procedure, the bromine must be removed from water because if water is present, then the FeBr3 catalyst will form it's hydrate and work work. Tetralin (to the best of my knowledge) will brominate wihtout a catalyst, which means that if it's added to an aqueous bromine solution, it *might* release HBr(g).
I haven't tried this, because I haven't located OTC tetralin. Tetralin is a turpentine replacement and may be found in a paint store. Also, it's the major component of "Cuprex" a trademark referring to a pest/pediculicide that was also sold as a lice shampoo of the same name. It seems to have gone off the market, so I dunno, but if you have an easy line on tetralin, that might work better for you.
blah blah blah something clever blah blah blah