As cool and useful as old trunks are, they don't seem to command very high prices generally. I've seen them under $100 for most of them, but a retail shops price them higher. The exception to the rule are sea chests that are actual sea chests and not mis-named trunks. Those can get way up there, especially if they have names or paintings. If you know the history of the trunk and the old owner's name is on it that can help too. Also if the old transport stickers are still there, those can be fun to read and to help date it. (FYI I'm not an expert)