Thanks to the advent of the Web, you don't need a printed catalog. But, if you don't have a printed catalog, then it's a must that you have a website/catalog online. But don't stop there!
Your website should include a Contact page that details how you may be contacted, which nowadays is mostly via email. When you respond to email inquiries, it is vitally important that you prepare a well written response that explains how you present your catalog and other information that will make the a potential buyer feel welcome and comfortable with working with you online. As an example, see http://www.greatrep.com/response_example.htm. You can modify this example to fit your situation. And make it appear to be personal, i.e. not some canned auto reply response.