5.00 IPOD (portable audio whatever) Amplifier.
I found these at Big lots and picked up a couple, they are 5.00 and you can remove the portable battery powered amplifier to use on whatever you choose.
It runs off 4 AAA Batteries and you can make the lil battery powered speakers sound like a lil boom box.
Inside there is a lil amp ran to a single speaker. Its screwed in from behind.