Alex identifies a number of different types of cost, which as Tom points out are largely monetary costs. But what is a cost anyway?
An enterprise incurs a great deal of cost. and these can be broken down and classified in various ways. Accountants like to express all costs in monetary terms – so for example, human effort is translated into labour cost.
But that only works if the enterprise is directly paying for the labour, in the form of wages or contractor bills. Wasting the customers' time doesn't count as a direct cost to the enterprise, although it may well have an indirect cost in terms of customer complaints and lost revenue.
We might also think of anxiety as a cost. As Seth Godin comments in relation to the airline industry, "By assuming that their customer base prefers to save money, not anxiety, they create an anxiety-filled system." Eleven things organizations can learn from airports (Jan 2013). See also my post on Anxiety as a Cost (Jan 2013).
Even for direct labour, the human cost may not be fully reflected by the wages and monetary overheads associated with employment. Many employees do unpaid overtime and incur other personal costs, and this is only visible to the enterprise accountants when it results in high levels of sickness and staff turnover.
So we need to remember the difference between a real cost and its monetary measure.