I found plastic bins at Staples that are 21 x 14 for $1.60 each. They fit my shelves perfect. I bought 10 of them and just labeled with masking tape. Oh, and they are clear plastic. I bought all the store had. Now I have bins for all my colors and for specialty fabrics like Christmas, batiks, 1930, backings, flannel, backgrds, etc.
The bins are about 4 in to long but are not a problem.
I have those cheap metal shelves that are cubby holes that you put those fabric (expensive) bins in.