It never really occurred to me that it would use up that much power, but I've just had a think. Apparently my dryer uses about 3.5kWh to dry a load (per the manufacturer's web-site,) this is for a 6kg appliance rated 'C' - which is not that efficient. According to the money saving expert the average UK energy price is about 12p per kWh - so it should cost me about 42p to do a load. We do 2, maybe 3 loads a week, so the dryer costs less then a Starbucks tall filter coffee.
That's of course using average figure for energy prices whatever the manufacturer counts as a load of washing but I can't see the numbers being that far out, certainly it should be in the same order of magnitude.