N.C. Gen. Stat. § 143-129.7

Notwithstanding the provisions of Article 12 of Chapter 160A of the General Statutes, municipalities, counties, and other political subdivisions of the State may include in specifications for the purchase of apparatus, supplies, materials, or equipment an opportunity for bidders to purchase as "trade-in" specified personal property owned by the municipality, county, or other political subdivision, and the awarding authority may award a contract for both the purchase of the apparatus, supplies, materials, or equipment and the sale of trade-in property, taking into consideration the amount offered on the trade-in when applying the criteria for award established in this Article.