It's possible to add expenditure items for a Vacancy, so to keep track of every single selection costs.
When you create a Vacancy, in the Tab.1 Publishing, you can set the budget expenditure items by clicking on Other Info and then defining the Budget.
Customisable
You can customize the Expenditure items by clicking on System Settings > Customisable fields > Vacancies > Vacancy Budgets
In the Analytics module > Vacancies are available the Budget and Bugdet for are Widgets, where you can find an overview of the Budget setted for all the vacancies.