The classic 1965 and 1966 is not only the most desirable Mustang; it is the most collected car in the United States and the most collected item of its decade. Luckily for collectors, these cars were well made, and there are a ton of them. Both years sold more than 500,000 units. Of the 1965 and 1966 Mustangs, the fastback is the most highly sought after and the rarest. However, prices for the iconic car are relatively affordable at around $45,000.