Mamma Moon Botique via Amazon offers 6 Reusable Smart Sheep XL Wool Dryer Balls for $18.95. Coupon code "26Z34FAY" drops it to $13.26. Plus, Prime members bag free shipping. (Non-members can spend $49 to bag free shipping; otherwise, it adds $5.85.) That's the lowest price we could find by $4. They purport to naturally soften laundry without chemicals or synthetics.