Bus Utility and Safety in School Transportation Opportunity and Purchasing Act of 2005 - Directs the Secretary of Education to provide grants, on a competitive basis, to rural local educational agencies (LEAs) to pay the federal share (75%) of costs of purchasing new school buses. Requires the Secretary, in providing such grants, to give priority to rural LEAs that: (1) are transporting students in a bus manufactured before 1977; (2) have a grossly depleted fleet of school buses; or (3) serve a school required by law to provide transportation to students to enable them to transfer to another public school served by the rural LEA.