Suppose Mabel decides to take a trip to South Dakota. Which result would be a cost?

 - Mabel will save some money. Plane tickets for Mabel to get to South Dakota are less expensive than tickets to Oklahoma.
 - Mabel will give up the chance to go to Oklahoma. She would have enjoyed a trip to Oklahoma more than South Dakota.
This result is a cost. It involves giving up or spending something that Mabel wants or needs:
Mabel will give up the chance to go to Oklahoma. She would have enjoyed a trip to Oklahoma more than South Dakota.