Average cost of wiring a new addition?

I've been looking at homes to buy and there is one I am very interested in. The only problem is that it has a small addition that still needs to be finished. I have someone who could do most of the finishing for the cost of materials but he cannot do the electrical work. So my question is, what is the average cost to add electrical wiring to an addition? I don't own the place yet, and I can't get a quote from an electrician until I buy it.