21-08-2013 16:14 - edited 21-08-2013 16:16
Cost varies depending on country and care point you use. Most Care Points and run by contractors and not by Nokia themselves. To get an estimate, you should really contact a few care points nearest you and see who is the cheapest.
As well as that, it will be a long time before you will need a replacement battery. They usually get cheaper over time.