According to the present disclosure, a method of providing item sales information by a computing apparatus is provided, the method including acquiring first selection information regarding an item, acquiring sub-item information applicable to the item in response to the first selection information, acquiring second selection information regarding the applicable sub-item information, and providing first amount information and second amount information in response to the second selection information, in which the first amount information is a cost corresponding to the item and is determined in response to the second selection information.