Those 10 million valentine’s day roses could instead have been grow in south America. Its seem extremely likely that the opportunity cost of those roses in term of computers would be less than it would be in the united states. For one thing, it is a lot easier to grow February roses in the southern hemisphere, where it is summer in February rather than winter. Furthermore, south American workers are less efficient than their U.S. counter parts at making sophisticated goods such as computers, which mean that a given amount of resources used in computers production yields fewer computers in south America than in the united states. So the trade-off in south America might be something like 10 million winter roses for only 30000 computers.