4. AAR Gurney Westlake Eagle – $3.74 Million
With a price tag of $3.74 million in 2013, this is one of the most expensive Formula One cars they ever sold. The Eagle F1 was the brainchild of the famous American racer, Dan Gurney. In fact, he designed and raced the car in the mid-60s. Amazingly, Gurney was the only person to win a Formula One race in a car he designed himself while driving for his own team.