I'm also looking into this fo a friend that sells chicks from his feed store. They used to use heat lamps, but their winter electric bill is really high, so they are looking for a low wattage solution to help offset that expense. I think they said that one month their electric bill was close to $1500/month, which is a lot considering they have no heat in the building.
Dimmer switches are an idea... I switched to using those with secured heat lamps and it dropped my electric bill immensely... I was super amazed at the difference it made...