I've never gone over $2,000 per night (and that was inclusive of meals), but if you want the big leagues, there are private islands for rent such as Necker Island, a 74-acre, private island northeast of Virgin Gorda that is owned by Richard Branson. It is available for rent to one group at a time. Rates for 2000 ranged from $14,000 per night for 1-7 guests to $22,500 per night for 20-24 guests.