my mother would use old drapes for quilt backs. she used denim cut from the back of the legs of ragged jeans also. she would use the denim for backing or for fronts depending on who the quilt was for. I buy fabric at rummage sales, thrift shops,goodwill,walmart,Joannes,Hancocks and Mill Ends. I save all my scraps and put them to use in scrap quilt tops for my church group. I check out remnant bins is the various fabric stores I go to. You would be surprised how many times you can find the just right piece needed to give a quilt some pizazz. one cute quilt I made was from five remnants I picked up for a quarter a piece from Mill Ends. They were the end of bolt strips of 4 blocks of Asian girls in various colored clothing. I cut 20 squares from these strips, framed them with solid strips and alternated with plain blocks cut from another remnant. total price of twin size quilt top was less than $5.00. happy fabric hunting and quilting.