A repeated point in Superfreakonomics is that big expensive problems do not require big expensive solutions.

Seatbelts, for example, are one of the most costs effective lifesaving devices ever. At $25 per installation it costs about $500 million to put them in every U.S. vehicle, or about $30,000 for every life saved. The per mile auto fatality rate is so low that you can drive 24 hours a day at 30 miles an hour for 285 consecutive years before you had a fatal accident.

Air bags which cost about $4 billion to have installed in the U.S. fleet end up costing about $1.8 million dollar per life saved; 60 times as much.

From ‘Superfreakonomics- Global Cooling, Patriotic Prostitutes, and Why Suicide Bombers Should Buy Life Insurance’ by Steven Levitt and Stephen Dubner