LOL okay, Walmart is good.
Any good sized bag can be a yarn/project bag. Even some diaper bags make great knitting bags. Mine wasn't marketed as a knitting bag. It was probably a beach bag, but it zips and has long handles which I like. I'm pretty sure Walmart has something that would work. Stay away from mesh and Velcro.
Here's an example. Mine is shaped like this.
http://www.walmart.com/ip/Wildkin-Pu...e-Bag/12179657