John has been offered a job in New York City at a salary of $50,000 per year. Currently, John lives and works in the Midwest at a salary of $35,000 per year. New York's standard of living is much more costly than in the Midwest. What type of costs would John consider in making a decision? Which would be "sunk" and which would be "opportunity" costs? Which are the differential costs? Are there "other" variables besides costs that John might consider, perhaps?