How much would a used, low mileage cert. eng cost

as much as a re built one. but it only has 90 day warranty instead of 3 yr 50k. companies like jasper, atk and probuilt re man motors and sell to shops for installation. i would allow about 2800 for the motor and the labor is 15 hours to change the long block. add about 500-800 for accessories. Roy