To estimate the price of the 2017 Isuzu D-Max I4 3.0L Turbocharged (Diesel) Double Cab with 321000 km mileage, I considered the listed prices of similar cars. The closest match is a 2017 Isuzu D-Max I4 3.0L Turbocharged (Diesel) Double Cab with the same mileage listed for SAR 43500. Other relevant data points include a 2015 Isuzu D-Max I4 2.5L Single Cab with 310867 km listed for SAR 49000, and several 2019 models with varying mileages and prices ranging from SAR 48500 to SAR 90000. Given the age and higher mileage of the target car, I adjusted the estimate downwards from the listed price of SAR 43500 to account for depreciation and market conditions.