You can get the cups at www.beaktime.com/water.php or on ebay. The nipples can be found on ebay, just pay attention to the different types and make sure you know what you want before purchasing since not all are created equal.
Also check out the nipple water cups. That is my preference so they can see the water and drink naturally. It is personal preference for which is better. They both work great with chickens and are much easier on you than standard waterers.