Are you talking about the ArtBin Satchels? You can get those at JoAnns (
http://www.joann.com/storage/craft-storage/). The best time to buy is when they have the 40 or 50% off storage sales. They are having a 40% off sale right now.
I have a bunch of them. I love them for projects. They are very sturdy. I definitely prefer them to the Iris brand.