it will cost the same as the u.s all they do is change the dollar sign for the pound sign so for us british people we pay more for it as i dont think they can be bothered to check and change exchange rate
Besides the simplicity of just charging the same number, don't you Europeans have the vat tax? Which if I understand covers just about everything, including digital purchases? If such is the case, you can hardly blame them for charging more.
Failing that, you have EU, and all its member countries having all sorts of different laws. *cough* German gaming board *cough* making life a nightmare for anything released.