The Nuby super spouts are readily available online in stores like http://shop.nubysippycup.com but are they available in any of the retail stores?
Most stores like Target, Walmart and Toys R Us boast of selling Nuby products and they do. However, it's easier to find the super spout cups (both the two handle no spill cup and the tall, 10 oz Nuby Super Spout Easy Gripper cup in the stores than it is to find the spouts. When you do a search on google for the spouts, oftentimes you will see the major stores advertise them. If you go to their websites, you will find that they don't actually carry them but they carry Nuby products. It's just a way to get you to their sites.
There are other stores who sell the Nuby super spouts online. Check all of the factors before you buy. A super low price might be great, but double check the shipping charges as well. You will want to get the best price overall because the babies and toddlers like to chew on the Super Spouts and they will need replaced eventually.