A friend pointed out to me a letter to the editor that was published on April 17th in the Daily Telegraph:

“Sir – In Britain at war (Court & Social page, April 16) a section entitled “Killing a German” reported an American statistician’s calculation that in the Second World War up to 1944, the cost of killing each enemy soldier was £12.500, up from 3 s 9 d in the time of Caesar.
Has any Ministry of Defence official calculated the cost to Britain of each Taliban fighter killed in the past 10 years? Paul Rutherford, Bishops Sutton, Hampshire”

This is an important question.
The cost of killing is something that is mostly overlooked by many statisticians and economists.
How much does it cost to execute a citizen in the U.S.? And how much does it cost the Chinese government to execute one of its citizens? What is the cost of killing enemy fighters by drone compared to an execution performed by an elite unit?
Economists keep track of the cost of a big mac in different countries, but I’d like to know what is the cost of hiring a contract killer in each of the world's countries. A wife wants to get rid of her husband. What does it cost her in the U.K.? What does it cost her in Nigeria? What does it cost her in Argentina? What are the risks in each different country? Which country offers cheap and reliable contract killers? We do not know the cost of living, if we close our eyes to the cost of killing.