People use sheets some times for backing or you can piece your backing. something that is also nice is making two quilt tops and using one on the back. Kind of like a reversible quilt. I do have a hard time positioning them the right way but maybe some others on the board can help with that. Also table clothes can be used for backing. Batting is hard. I tend to prefer putting out the money and buy poly batting if my budget is low versus using old blankets etc. It also helps if you can buy it in bulk like on the roll but at the same time that is a big expense all at once. In Europe sometimes they have old wool blankets. I have thought about trying to use those as I have some from Europe but I wonder if it is a bit too heavy. How about felting old Shetland wool sweaters and piecing the batting that way?