If Tennessee Republican Congressman John Duncan is to be believed, we spend $860 million for the Air Marshal Service. They make an average of 4.2 arrests per year. Not per officer. But the entire agency. That works out to $200 million per arrest.
Now I'm the first to say let's not judge police by arrest stats. But...
I would like to see some evidence that the Air Marshals have prevented anything (except the occasional Qatar asshole with diplomatic immunity smoking in the bathroom.)
Also, if the average Air Marshal makes $100,000 a year in salary and benefits, and let's throw in $100 million a year for guns and paperclips, where does the other $459,000,000 go?
According the congressman, there have been more arrests of Air Marshals than arrests made by Air Marshals.
[Full disclosure: Soon after I quit the Baltimore Police Department and was writing my PhD dissertation, I looked into getting a part-job with the Air Marshals. What could be better for a graduate student than--after a careful visual inspection of the plane, the passengers, and any potential threats--being paid to sit around and do nothing? And my offer still stands. Even as a temp. For free! Just pay for my training and give me a free ticket whenever I fly. I'll keep people safe.
Alas, the Federal Air Marshal Service does not hire part time.]