It costs a fortune. Basing my knowledge from when Holland joined the Euro, all the prices had to be changed and it cost businesses and more importantly people a lot of money. Same happened to Estonia last January and it pissed a lot of people off. Joining the Euro is not an option, it's only going to get worse imo. But I agree, if you're going to have independence, you have to go the whole hog and change the currency or the govt will be at the mercy of the Bank of England.