To reply to the original post:- I don't worry about matching but do try to coordinate. I always make the binding to either match or compliment the front. For scrappy quilts I've pieced the backs and if I don't have enough fabric I'll try to add something that goes with it.
A friend has a lovely idea which is easier on her bank balance as she is a widow on a fixed income. She takes what you call muslin but we call calico and embroiders Redwork randomly over it. Great for kids quilts as it's an extra surprise. Not always red either.