Post links to the sites where you have them listed, if that's how you're doing it.

If you're listing them to sell through Mudcat, you'll have to work out how to communicate. If members respond, you can send personal messages through the Mudcat site. Otherwise you'll have to post email, phone, etc. info. If you want that removed after the sale, let one of the moderators know and we can take out the contact information (leaving the sales info intact, as a source of information regarding instruments and current sales prices).