Another way of buying a used car is through rental agencies. Find used car at those places, for instance, Enterprise Rent a Car. They sell hundreds of cars at below Kelley Blue Book value. Remember that car rental agencies buy fleets of cars and Enterprise Rent a Car unload several hundreds periodically out of more than 700,000. To sweeten the deal, they even allow you up to 7 days or 1,000 miles to return the car of your choice. Except for some scratches and scrapes, their engines are probably maintained better than privately owned cars, as they are kept in constant care and maintenance during use.
Rental cars from the top companies are clean and seldom break down. The companies tend to take them out of service by one to two years of age, so you are getting a decent car which the rental company has already absorbed the largest portion of the depreciation. Rental car companies tend to use no haggle pricing, as they just want to reduce inventory to give way to newer models.