For purposes of section
501 of title
40 (relating to Federal sources of supply, including lodging providers, airlines and other transportation providers), a tribal organization carrying out a contract, grant, or cooperative agreement under this subchapter shall be deemed an executive agency and part of the Indian Health Service when carrying out such contract, grant, or agreement and the employees of the tribal organization shall be eligible to have access to such sources of supply on the same basis as employees of an executive agency have such access. For purposes of carrying out such contract, grant, or agreement, the Secretary shall, at the request of an Indian tribe, enter into an agreement for the acquisition, on behalf of the Indian tribe, of any goods, services, or supplies available to the Secretary from the General Services Administration or other Federal agencies that are not directly available to the Indian tribe under this section or under any other Federal law, including acquisitions from prime vendors. All such acquisitions shall be undertaken through the most efficient and speedy means practicable, including electronic ordering arrangements.