I am with Tartan - it really is a crap shoot. It can shrink in both width and length. I have bought it from Walmart, Joann's, Beverly's, Fabric.com, and the list goes on. I order based on what goes with the rest of the quilt or that I think is cute. One quilt I was making with Disney Princesses - found some on-line for $9.00+ a yard which seemed pricey. Went to Walmart found one extremely similar of $2.95 a yard and it washed up fantastic. I had another one that I paid a lot for because it was so pretty, and it looked like I shaved it. (Thus the reason I bought the less expensive Disney fabric because if it fell apart the investment wasn't as much.)
It is rare when it goes bad - but it does happen.