Use energy-efficient light bulbs if you're looking to cut as much energy costs as possible. This particular model has a so-called GX24q-1 socket, so make doubly sure that it will fit.
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Osram 13 Watt Compact Fluorescent Light Dulux T/E Plus Lamp
LED Bulbs
Osram 13W Dulux CFL TE 4 PIN Cool White - OS446967
Big on Electricals
Osram 13W Dulux CFL TE 4 PIN Cool White - OS446967