Pat
Go to Hobby Shop that specializes in model trains, more specifically "HO" scale trains. A good shop will have a selection of aftermarket items including brass locomotive bells as well as white metal bells. While the "HO" scale bells might not be accurate for all 1/350 scale ships, they would be appropriate for many larger ships. Also "N" scale could offer aftermarket bells if you can find a shop that carries this smaller scale. Most good train shops have Walthers' HO and N train catalogs(it's thick as a phone book) , perhaps you can locate what you are looking for. Good luck.