My Target store recently had some EcoTools body and foot sponges on clearance for under a $1 so I scooped up a few.
I've used their earth-friendly products before and like them.
The bath sponge is made from plant pulp and doesn't contain nylon and polyester.
The foot sponge is made from crushed walnuts and natural cellulose.
Both bath buddies are soft and gentle on the skin. You can order them here.
Photos from http://www.parispresents.com/EcoTools_s/36.htm.