My iPod got washed, where can I find a battery?

My iPod got washed a full cycle in the washer. I got it dried out completely. After some time, it will now come on and work fine as long as it's plugged up. I can eject it and it will show all my songs the camera will record video save files etc. It all works fine. If you actually unplug it from the computer it just turns off completely. Any one know where i can find a battery to replace the old one myself ? Since everything works hooked up seems if i replace the battery i should be fine. Any suggestions?