If it's council oap bungalows (4 windows and the door) I'm charging £4.50 a place, and they take no time at all, if you are friendly you'll end up with all the neighbors as well. It's tough to stick to a high minimum price on this type of work, as the customer knows exactly how long you've been.
Other bungalows go for normal prices, as soon as you need a point if done traditionally it's a hassle.
Simon.