I buy Walmart fabric and really don't have a problem quilting with it. My grandmother quilted from the time she was a young girl until she was a "grandma" she used fabrics from old work clothes and dresses. I have two of those very old quilts and they are treasures. Nobody really spent money on fabric for quilts back then.
My Walmart closed it's fabric department to enlarge their electronics department. I am very unhappy about this. It was the only place that I could go to get fabric without making a trip out of it. The closest place now is Joann's and it takes a good 45 to 50 minutes to get there.