Radioshack part number 272-1092 comes in a pack of 2 for like $1.99 or something.
Then pull the switch out, turn the little bulb carrier out, and follow this write up of how to replace the bulb in the carrier. All back together and done. I've used 4 of these radioshack bulbs so far in switches and HVAC units replacing the OEM ones as they go out and they work well.