I have fabric from all sorts of places. We have Alco here and they have fabric, some of it the high end names at affordable prices. We were told from the manager that some of it is end runs, other is last years patterns printed on lower thread count fabric, and some of the company's will sell their patterns.
When I buy fabric at the discount stores I just make sure it had a decent weight/thread count to it. And I always prewash in case it shrinks more.
But even at a quilt shop I check weight if I don't recognize the name of the manufacturer on the bolt. We have a shop here in town that sells some stuff that isn't worth $8.00 a yard and it should be in cheap bin at Wal-Mart