Might be a good idea to sell an electric engraver and or stamp kit in your store too... Also, if you could make some kind of rim and or a spacer on it that held it closed tight with a padlock I think you might sell more. As is the tamper tag with a padlock would only tell you if it had been compromised not keep people from peeking if they were determined.
A small metal ring might make a good spacer as well.