A retailer purchases a seasonal product from a supplier for $$3/$unit$,$ which it then sells to customers for $$10.$ Customer demand for the season is forecasted to be a normal distribution with a mean of $2,000$ and a standard deviation of $750.$ If the retailer orders once from the supplier before the start of the selling season and salvages unsold units after the end of the selling season for $$2/$unit$,$ what is the retailer's optimal expected profit in dollars?