how to independently light up a 4" model street lamp?

light-up model street lamp, 4" tall, 14v.i need to be able to light it up without a model train power converter. 

Some model suppliers stock 'grain of rice' bulbs, and smaller, specifically for this purpose, although I'm unsure as to the exact voltage requirements.
What kind of bulb does it have ? Replace it with an LED, and you can power it with a coin cell.