Yep, you sure can purchase them separately. There are two sizes. I'm not sure how much the little one costs, but I recently (after the last price increase, I believe) purchased the larger one in the chocolate brown leather (the one that goes with Damier Ebene) and it was £33 (about US$51). I just called my nearest store and had them hot stamp it for me and mail it to me. You can't buy them online but I believe you should be able to order them over the telephone and if not, they'll connect you to a store that has them in stock and they'll do a charge-send.