Use energy-efficient light bulbs if you're looking to cut as much energy costs as possible. On this light bulb you'll find a GX24d-3 socket.
From Amazon
Osram Dulux T/E GX24Q-3 26w Watt Warm White (3000k) Compact Fluorescent Light Plus Lamp, G24d, 26 W
LED Bulbs
Osram 26W Dulux CFL T 2 PIN Warm White - OS342061
Big on Electricals
Osram 26W Dulux CFL T 2 PIN Warm White - OS342061