Gray is not familiar with the TCO concept. How should Susan explain it to him?

What will be an ideal response?

Total cost of ownership (TCO) includes direct costs and indirect expenses that contribute to the cost of the new system. Some costs might be hidden, and a system that seems inexpensive initially actually might turn out to be much more costly.
You also can mention that Microsoft found that indirect costs have tripled over the last 10 years and now account for almost 50 percent of total costs. Microsoft also points out that most indirect costs, such as end user peer-support, self-support, and downtime productivity losses, typically were not included in IT department budgets and unaccounted for in most companies.