Sign up for coupons at Jo-Ann's. Hancocks, and Michael's.
Show your quilt guild membership card at quilt shops. This is usually 10% or 15 %.
Sign up for e-newsletters at quilt shops so that you know about sales.
Some shops give you a discount on your supplies when you take a class there. For example----Nancy's Calico Patch in Newport News gives you 20% discount on supplies at her shop.
Some weeks there are coupons in the newspaper for needlework/fabric shops.
Years ago I took a quilting class and learned that muslin or a cotton sheet was a relatively cheap quilt backing.