Al Qaida in Iraq keeps excellent books, which some Rand Corporation analysts got a hold of and used to conduct a forensic audit to figure out how Al Qaida functions. Very efficiently, it turns out. But the pay's no good.
According to the recovered financial documents of Al Qaida in Iraq's Anbar Province subsidiary, the group is highly organized, bureaucratic, and profitable. In 2005 and 2006, the time period covered by the documents, the Anbar organization was pulling in an average of $373,000 per month through blackmail, extortion, and selling stolen goods. It was often making a profit, and sending excess revenues to Al Qaida in Iraq's general fund or even operations in other countries.
By cross-checking Al Qaida's revenues against recorded terror attacks in Anbar, the Rand researchers concluded that each attack cost $2,732. That's a lot compared to what Al Qaida pays in terms of salaries—$491 per year for a militant without a family, with more pay for more dependents: "Individual members of Al Qaida made less money than ordinary Anbaris—AQI average annual household compensation was $1,331 compared to $6,177 for average Anbar households—but faced a nearly 50-fold increase in the yearly risk of violent death."
Aside from terrorism, Al Qaida liked to spend its money on border control, a functioning judiciary, and its own mail system. About 5% goes to "payrolls and medical." No word on whether that includes dental.