The option to build two advanced Aegis destroyers to protect Japan from the North Korean missile threat would cost over 500 billion yen ($4.8 billion), more expensive than the scrapped plan to introduce a land-based interception system, sources close to the matter said Tuesday.The government has been seeking alternatives since its decision earlier this year to scrap the plan to deploy the U.S.-developed Aegis Ashore system in northeastern and western Japan due to technical problems and ballooning costs.The estimate, compiled by two companies commissioned by the government, compares with the 40…