Final answer:
The finder's fee for High Roller Inc. is a relevant cost for the decision between buying or leasing a private jet, as it is a future cost that will only be incurred if the jet is purchased.
Step-by-step explanation:
The finder's fee associated with the purchase of a private jet for High Roller Inc. would be considered a relevant cost for the decision-making process. A relevant cost is one that will occur in the future and is directly related to the business decision at hand. In this case, if High Roller Inc. decides to buy a private jet, the finder's fee is a cost that they will incur and must be taken into account when making the decision between buying and leasing a jet.
Conversely, sunk costs are costs that have already been incurred and cannot be recovered. When making decisions, sunk costs should be ignored, because they cannot be changed by any future actions. Since the finder's fee has not yet been paid and will only occur if the jet is purchased, it is not a sunk cost.