I by bolts of good quality white and unbleached muslin from my local JoAnn's when I have a 50 % or 60% coupon. I know what I like to use frequently and that is what I get. My next purchase will be a bolt of the wider muslin so I do not have to piece the backing as frequently. It is a leap to lay out that much money, but what a pleasure it is to go to my stash and have what I need on hand and not need to zip off for those basics. A second benefit is that my scraps all match, rather than having a pile of white scraps that are all just slightly different when I want to use them for a secondary project.