I don't have time to read thru all these answers. It is a myth that only quilt shop fabric is better.
Fabric Manufacturers do not have the luxury of buying different grades of base fabric for different markets.
Some manufacturers as a general policy may do lesser quality than others but you find excellent quality at quilt shops as wel as any and all of the chains. There may have been a time when chains only had poor quality but not any more.
Lets learn to feel and test the quality and make the decision for ourselves. I have used fabric from the same manufacturer and in the same design line and some of it had a different feel in quality than others. Sometime it depends on where the fabric is printed. Please lets get rid of this myth and learn to test the quality ourselves.