N.H. Rev. Stat. § 228:32
The commissioner of transportation may sell to other departments and institutions of the state and to subdivisions of the state, materials and supplies purchased for use by the department in connection with their normal operations. He is authorized to assess a fair and equitable charge with respect to the materials and supplies, sufficient to defray all administrative, warehousing, processing, distribution and transportation costs incurred by the department in providing this service. Payments received by the department from these charges shall be credited as income added to the appropriation accounts from which the expenditures were originally charged, so that the resale of items purchased for departmental use will not cause a reduction in funds available for the operation of the department.
RSA 228:32
RSA 229:10-a. 1965, 350:1. 1981, 87:1. 1985, 402:6, I(b)(1).