i don't know where you are but in the states try www.keptforher.com Prices and shipping are the most reasonable i have found. MM's sweetpea rachel
www.cb-2000.com sells them also, and they tell you that the rings are interchangeable between CB2K, CB3K, and Curve. Their site isn't the easiest to navigate, but if you follow the links as if you are buying the CB3K, you will get to the page where you can order individual rings.