Given the lack of specific data points such as selling prices, offers accepted, or listed prices for similar cars, I will use the new car price and apply depreciation logic. Assuming a new car price for a 2020 Alfa Romeo Brera 2.4L Standard is around 200,000 AED, and considering a depreciation rate of 10% per year, the car would depreciate by 20,000 AED each year. Over four years, this totals to 80,000 AED in depreciation. Therefore, the estimated price would be 200,000 AED - 80,000 AED = 120,000 AED. Additionally, considering the high mileage of 300,000 km, which is significantly above average, I will further reduce the price by 20,000 AED to account for the wear and tear, resulting in a final estimate.