The commissioner of transportation may bill highway operations units of the department and local road authorities for the costs of a centrally managed highway sign program. These costs may include equipment acquisition and rental, labor, materials, and other costs as determined by the commissioner. Receipts must be credited to a special account, which is established in the trunk highway fund, and are appropriated to the commissioner to pay the costs for which the billings are made. Amounts credited to the account are exempt from statewide and agency indirect costs payments.