Ironically enough, every statement you make is an externality - an effect or impact that does not impact the microeconomics of the transaction, but may profoundly effect or impact the macroeconomics of the larger system within which the microsystem dwells. Externalities, of course, make up the bulk of the arguments within Freakonomics, the blog of which is the source of this argument. One of the many reasons I hate Freakonomics.
If you're going to comment on how cheap something is and use that as an argument, you need to dig into WHY it's cheap. All of your arguments are about externalities as to why it's cheap. None of these arguments about externalities were raised by the Freakonomics fuckwits because they completely undercut their point... when 90% of the time, when the Freakonomics fuckwits want to make a point, they go in search of Wild Externalities. Externalities aren't bad, they're just things that aren't necessarily accounted for in the main discussion. Which is why the article is such bullshit.
Why would that be a reason to hate Freakonomics, though? Just wondering.