Actually, the ones I just made were completely free.

Cut three strips from an old bath towel. The kind with nubs works best. I cut the strips about 3-inches wide across the width of the towel.

Take one strip and tie a loose overhand knot in the center. Slip the second strip through the knot and tie another overhand knot. Slip the third one through the first two and tie a third knot. Pull the ends of the strips to tighten all the knots and form a small ball in the center.