What are oscar's compensatory damages in this case?

Advertising expenses that he already paid.

All of these.

The money he already paid Spud in advance.

The cost to finish the job.

-Compensatory damages compensate the injured party (in this case Oscar) for damages that arise solely from the contract and the breach thereof. The compensatory damages are intended to make the injured party whole. All of these would directly compensate for the loss.