The Defense Logistics Agency (DLA) Law Enforcement Support Office (LESO) administers the DOD 1033 Program, which provides free materiel to local law enforcement agencies that request it. The LESO notes that it transferred over $449M worth of materiel in 2013. That's about $1.43 per capita, assuming the entire cost was funded with current year appropriations. The program began with the NDAA for FY1997, so any comparison with results should start at that year.
The materiel in question includes armored vehicles, body armor, night vision equipment, surveillance devices, and other implements intended for use in high-threat tactical situations. It is appropriate to consider whether situations requiring such equipment have occurred with more or less frequency since 1997. It is also appropriate to consider the cost of crime as an opportunity cost that more robust policing should mitigate. Slate notes that intermittent efforts to calculate the costs of various crimes have periodically filled our knowledge gaps. I did not see statistics in that article for the cost of high-threat tactical situations. Mark Cohen's landmark 1998 study "The Monetary Value of Saving a High-Risk Youth" is focused on the cost-benefit relationship in crime prevention, not high-threat tactical situations.
Let's consider other tools. The RAND Corporation's Cost of Crime Calculator allows citizens to compare the costs of crime in their neighborhoods. RAND's "Hidden in Plain Sight" study concludes that investing in police personnel (i.e., the number and quality of the humans in the force) has a favorable cost-benefit result. It does not specifically cover high-threat tactical situations or use of materiel, but it points the way to understanding how to frame them. "Hidden in Plain Sight" compares the annual cost of crime in a locality to that area's gross municipal product (GMP), aka gross metropolitan product. Analysts can thus isolate the cost of a singular high-threat tactical situation, such as arson damages from a riot or sales lost due to store closures during a protest, and compare it to GMP. We can then compare that financial loss to the cost of DOD 1033 Program materiel used to mitigate said situation to determine a cost-benefit relationship.
Analysts have national data standards on crime costs. The FBI's Uniform Crime Reports aggregate crime data for all US municipalities, now updated with the UCR Data Tool for searches. The NIH study "The Cost of Crime to Society" outlines standards for sensitivity analysis and endogenizes intangible costs that will likely follow most violent criminal events. Analysis of high-threat tactical situations should adjust the NIH's base cases for the cost of DOD 1033 Program materiel committed to violent crime incidents.
This framework is only the beginning of a cost-benefit analysis. Every municipality should run the numbers for DOD 1033 Program materiel deployed in response to local violent incidents. High-threat tactical situations such as riots, bomb threats, and active shooter hostage situations are infrequent but dramatic. Anecdotal reporting suggests that police forces are inclined to use military-grade gear to perform routine functions, with little regard for utility, fuel cost, or maintenance needs. Serving a search warrant is obviously cheaper on foot than in an armored personnel carrier. Municipal police forces should ask themselves whether their community's criminal statistics justify requests for heavy gear that they may never need. Citizens in a free society have a right to ask whether a gas-gazzling surplus MRAP has a better cost-benefit result than a standard police cruiser.