According to Official Guinness Records,
The most expensive hamburger sells for $5,000 (£3,115.87) and is prepared by Juicys Foods and Ovations Foodservices for Juicys Outlaw Grill, based in Corvallis, Oregon, USA, as of 2 July 2011. The hamburger weighs 352.44 kg (777 lb) and is available for ordering with 48 hours notice for preparation time.
For a complete list of 2011 records, please visit 2011 Guinness Records in United States.