A firm's manager must decide whether to make or buy a certain item used in the production of vending machines. Making the item would involve annual lease costs of $150,000. Cost and volume estimates are as follows: Annual fixed cost Variable cost/unit Annual volume (units) Make Buy $150,000 None $ 60 $ 50 12.000 12,000 a. Given these numbers, should the firm buy or make this item? b. There is a possibility that volume could change in the future. At what volume would the manager be indifferent between making and buying?