M & S Factory has the following inventory information March 1 Beginning Inventory 40 units at $10 March 4 Purchases 70 units at $15 March 5 Purchase Returns 10 units at $15 March 12 Sale 60 units sold at $20 March 12 Sales Returns 20 units March 22Purchases 50 units at $18 The cost of goods available for sale at the end of march is