I have bought the extra muslin (108" and 120") from Fabric.com for backs and really love it. I have bought several bolts of muslin - unbleached, bleached and tea-dyed - in various widths and have always loved the quality and feel. It is a really nice smooth almost sateen finish. I have even used the bleached to dye my own backs. AND their free shipping starts at only $35. I have never been disappointed with anything that I have bought there. And they also carry the bamboo/silk batting which I just LOVE!!!!!