Save LOTS of cash by making your own eraser sponges from cheap ingredients. Mix 1 cup of baking soda (stock up on this when you see at the Dollar Store, it has so MANY uses!) with 1/2 cup of water to form a paste. Add 1/2 cup of liquid castile soap. Stir then pour this solution into an ice cube tray. Let this sit for about 4 hours (on your countertop) until it solidifies. Then use one at a time to clean any grime you may have.