About Simulation Costs
Resources can also have cost attributes:

a flat usage cost for any access which is not based on time
OR

a fixed cost per time period
OR

a variable cost per time period which is associated with non-consumable resources or a variable cost without a time period which is associated with consumable resources.
Some examples of cost types:
Consumable resource with variable cost
Fuel is an example of a consumable resource with a variable cost. If fuel costs $3 a gallon, $3 is its variable cost. Every time a unit (gallon) of fuel is used, a cost of $3 is applied.
Non-consumable resource with variable cost per period
An employee paid hourly is an example of a non-consumable resource with a variable cost per period. The employee's hourly pay can be defined as a variable cost of $30 per hour.
Non-consumable resource with fixed cost
A salaried employee is an example of a non-consumable resource with a fixed cost. The employee's annual salary can be defined as fixed cost of $30,000 yearly.