engaged in cultural, educational, or recreational activities (as defined in section 3306(a) of title 40, United States Code) at the prevailing rate for similar space, facilities, equipment, or services in the vicinity of the National Indian Program Training Center: Provided further , That all funds received pursuant to the two preceding provisos shall be credited to this account, shall be available until expended, and shall be used by the Secretary for necessary expenses of the National Indian Program Training Center: Provided further , That the Secretary may enter into grants and cooperative agreements to support the Office of Natural Resource Revenue’s collection and disbursement of royalties, fees, and other mineral revenue proceeds, as authorized by law. Administrative provision There is hereby authorized for acquisition from available resources within the Working Capital Fund, aircraft which may be obtained by donation, purchase or through available excess surplus property: Provided , That existing aircraft being replaced may be sold, with proceeds derived or trade-in value used to offset the purchase price for the replacement aircraft. office of natural resources revenue For necessary expenses for management of the collection and disbursement of royalties, fees, and other mineral revenue proceeds, and for grants and cooperative agreements, as authorized by law, $147,330,000, to remain available until September 30, 2021