The price premium is a result of the higher cost of production and distribution for organic food as well as consumers' willingness to pay more. According to the USDA Economic Research Service (ERS), relative changes of supply and demand will determine whether price premiums continue for organic farmers and businesses. If supply begins to grow faster than demand, price premiums will decline.
For more information see the USDA ERS Organic Farmgate and Wholesale Prices at http://www.ers.usda.gov/data/organicprices/ and The New Farm Organic Price Report from the Rodale Institute at http://www.rodaleinstitute.org/Organic-Price-Report