I don't know about the $50 Jeeps, but after the end of WW2 there were some incredible (by today's standards) deals on used military equipment. Frank Tallman of Talmantz aviation - the firm that did most of the movie stunt flying in the '50s, '60s, and '70s - bought something like 25 former military aircraft for a price worthy of Jason. He stuck the gas tanks, calculated how much gas there was in the aircraft, and bid the value of the gasoline. He got the aircraft and flew them away.