$10.99
USBBattery
BlueRed

Which power source is best?

USB is good for displays that will be left on for some time.  No need to changed the batteries.  The battery version includes 2 LR41 batteries, making it easy to play with or move around often.  The minifig can stand on top of or near the battery brick.  You can even use the battery brick as a handle to move the character.