Every store that sells fabrics have different quality fabrics. Not everyone makes heirloom quilt or any quilts. People use fabrics for all kinds of projects. Buying over priced fabrics doesn't always mean they are better quality. Usually feeling fabrics will help you determine the quality or lack thereof.
I make lots of donation quilts and since I buy everything for them I usually make them out of mid range fabrics as that is what I buy for all my quilts.