In business, opportunity cost is the amount of revenue or gain that is forgone by choosing one investment over another. For example, if faced with the choice of purchasing an eCommerce platform and a CRM, the opportunity cost of the eCommerce platform would be the amount of revenue that you lose by not having online sales. The total cost of ownership is a completely different animal. This metric calculates the total amount of money a company must expend to purchase and maintain an asset. It includes acquisition costs and ongoing and recurring costs. It does NOT include the opportunity cost.