I take it you are referring to the 10 day world ticket? If so, shop around as everyone seems to be undercutting each other. For a 7 day hopper I'd try an american broker such as ticketmania as they tend to work out better value (especially with a good exchange rate). Ticketmania do not charge P&P to send to UK, and I've never had any problems with them. Don't forget if you buy a 7 day hopper, unused days do not expire, but the 10 day world ticket isd only good for that one trip!