1) How much money would it have saved to enlist Iraqis to fix the infrastructure they knew instead of pouring billions into contractors to fix infrastructure they didn't know? This would have not only saved money, but two other problems for the military. One, local people are less likely to blow up systems they are working on, and two, young people would have busied their time in the employment of bettering their up and coming nation instead of joining insurgencies.
2) How much money would it have saved to keep our military at proper numbers instead of fooling ourselves into thinking that we are saving money throughout the 90s? The money we saved merely quadrupled when it came time to ride the backs of our military and counter their lack of numbers with paid mercenaries. Keeping our military at proper numbers would not only have saved money, but also solved two problems for the military. One, all combat personel in the AO would have been under military jurisdiction, and two, the image of the military would not have had to rest on the conduct of unprofessional civilian agents.
Neither Iraq nor Afghanistan should have cost as much as it did. And please don't default to "we shouldn't be there." If the borders of the greater Middle East cannot be amended to reflect the natural ties of blood and faith, we may take it as an article of faith that a portion of the bloodshed in the region will continue to be our own. Pretending that we don't have to be there or involved from time to time is not practical. It only compounds the treasure and blood in the end.