Hobby Lobby has lots of flannel, even solid colors. The Dollar stores carry the infants receiving blankets that are flannel and that would work as well. Look for sheet blankets too.
I made one rag baby quilt with flannel, never again, too much work trying to get it to shed the fuzz. And it will shed fuzz every time it is washed, I suppose, so I didn't give it away.
Carol J.