Walmart offers these Disney Cars Diecast Model Cars in DJ, Jonathan Wrenchworths, Billy Oilchanger, and Aiken Axler for $3.71. Opt for in-store pickup to dodge the $4.97 shipping charge. That's the lowest total price we could find by at least $4 for any character. Each car is a 1:55 scale model.
Of note, Walmart also has Giuseppe Motorosi for $3.99 with free in-store pickup.