Private auction firms sell surplus and retired military vehicles. As of April 2015, the two firms that handle the majority of these auctions are Government Liquidation and GovPlanet.
Government Liquidation and GovPlanet are the most reputable sites as they are the only ones currently contracted by the federal government to directly auction military vehicles. State and local charitable organizations often receive donated vehicles and then resell them. These are well-known and reputable charity organizations such as the Red Cross or the Boy Scouts. Buyers should check military vehicles sold by other organizations carefully, as the government can unwittingly repossess stolen vehicles.