Researchers at RAND got hold of data on Al Qaeda in Iraq’s expenditures by sector.  They also have data on attacks by sector.  They claim:

[W]e find that for every $2,732 transmitted by the Anbar administrative emir to a particular sector, an additional attack occurred in that sector….We compute the $2,732 figure as follows. Each spending coefficient
shows how much a $1,000 change in spending in a given week would change the number of attacks. Using the coefficients in Table 5.3, increasing expenditures by $1,000 in a week would increase the number of attacks by 0.1 in the same week, by 0.08 one week later, by 0.08 two weeks later, by 0.04 three weeks later, and by 0.06 four weeks later, for a total of almost 0.4 additional attacks. To convert this to the additional expenditure needed for one complete attack, we divide $1,000 by 0.366 (the exact fractional increase in attacks) to get $2,732.

They add:

The amount $2,700 is equivalent to almost three times Anbari per capita 2007 household income (in 2006 dollars) and 40 percent of total average household income, a relatively large sum.

I assume the data cannot be shared.  Otherwise, if the empirical analysis is sufficiently rigorous, the research is publishable in a peer-reviewed journal. These typically require data to be made publicly available so the analysis can be verified.