This can vary greatly from where you live and your credit rating, this would be a better question to ask your local utility company.
whats the average cost?
Well I would have to say I pay about 800 a month for it, I have a friend and he pays a 1000 for it, and then my sister pay 350 a month for it. Or do you want KWH, I pay 9 cents a KWH, and then my business pays about 15 a KWH. The price can vary a lot from person to person.