Suppose Charlotte decides to go on the roller coaster. Which result would be a cost?

 - Charlotte will save some ride tickets. She needs fewer tickets to go on the roller coaster than on the flying bobsled.
 - Charlotte will give up the chance to go on the flying bobsled. She would have had more fun on that ride.
This result is a cost. It involves giving up or spending something that Charlotte wants or needs:
Charlotte will give up the chance to go on the flying bobsled. She would have had more fun on that ride.