Better quality fabric will produce a better quilt. Cheaper fabric will stretch and ravel more. And the quilt will wear out sooner. After all the work put into making a quilt you want it too last.
I am on a fixed income and buy my fabric at a local quilt shop. But can't afford everyday prices. She has 2 sales a year, I buy my fabric during these sales. This way I get a good quaility fabric, but at reasonable prices I can afford. Cheap fabric will not produce a good quality quilt. You will not be pleased with the end result. In my opinion its bettter to buy less yardage of better quaility fabric than a lot of cheap fabric. Check with your local quilt shops and see when they have their sales. Check out the difference in the cheap/quilt shop quality. A lot of difference.