The highest expected profit is $$235,000$ if the machinery is sold at $$300,000.$ While setting the price at $$230,000$ increases the chance of a sale it reduces the revenue when it does sell. The higher price of $$390,000$ increases the revenue but significantly decreases the chance of making a sale. A selling price of $$300,000$ is the optimal balance between the probability of a sale and the revenue from that sale, leading to the highest expected profit when considering the option of keeping the machine in inventory.