The Fashionation company has a line of small and inexpensive cube and pyramid shaped 3.25-inch speakers. They are made from recycled materials and requires no batteries whatsoever to run.
These earth-friendly speakers are made from recycled materials and not only sound great, but help save the environment too. Each speaker folds flat for convenient storage and portability. Universally compatible; no batteries required.
The Eco-Speakers ($14.95) are available in a wide range of color options.