I'm afraid I must descend. I agree with the poster. I would rather put a coordinating solid color sheet on the back, than to just throw some non coordinating pieces of left over fabric on the back. Of course, if you wanted to cut that fabric up into 1002 small 2" squares, then you might just have something sorta pretty. But I agree, I have seen some pretty quilts ruined by what some people put on the back. Would you buy a quilt from a store looking like that?
Don't get me wrong, I certainly understand about the cost issue. I just think there are better alternatives than to just slap together a mismatched hodge podge on the back.