The first time, I bought a quilt kit from Joann's. It was all the way in the beginning when I learned to quilt. There were so many pieces of fabrics that were too short that I still haven't finnished the kit.
The second time it was more a stack of fabric to make this nice pink and green strip style quilt. I bought it at a major quilter's convention from a beautiful booth that had the quilt displayed on the wall. All the fabrics in the booth where quilter's quality as where the ones used in the quilt. I asked if the bundle could be opened up but they would not let me. I asked if it was all quilter's quality and they said, "Yes!" Well you can guess it. Some looked like craft fabric cheese cloth and went straight into the trash. Never mind the number of pieces that were too short. It has been years but I have never bought anything at that booth any more and neither have my friends. Arghhhh!!!
My best experience has been with kits that came directly from the manufacture with the exception of the Joann's bought kit mentioned above. The same with stacks of fat quarters.