RE: cheap target material?
Get a big woven bag. I use a horsefeed bag, with weeve big enough to let the arrows slide between the fibers without tearing it open. Fill the inside with plastic grocery bags collected from recycing places or from your kitchen. start stuffing bags into one big grocery bag, then tie it off and squish it flat so its like a big bag pancake. Layer the pancakes in the feed bag and tie it off....hang in a tree and voila!
Evan