A manufacturer of lapel buttons test marketed a new item at the University of California, Davis. It was found that 900 items could be sold if they were priced at \(\$ 1\), but only 300 items could be sold if the price were raised to \(\$ 7\). On the other hand, the manufacturer finds that 600 items can be supplied at \(\$ 1\) each. If they were supplied at \(\$ 9\) each, overtime shifts could be used to raise the supply to 1,000 items. What is the optimum price for the items?