Stone Company manufactures two products that incur joint costs of $60,000. It costs an additional $10,000 to produce 5,000 units of Product 1 and an additional $30,000 to produce 10,000 units of Product 2. Product 1 is sold for $8 per unit, and Product 2 is sold for $10 per unit. If the company uses the net realizable value method to allocate joint costs, the cost per unit of Product 1 is