it should cost very little. I don't know the actual wattage consumption, but is probably around 20 watts, which means: 1000 divided by 20 = 50. therefore it would run for 50 hours for the cost of 1 kw of power at about 10 pence a kw. so for a week it would be less than 40 pence. if you know the cost of your electricity you can work it out exactly. the consumption is normally etched into the transformer plug.