Myth. The hammer was only $435.
the truth of the matter in these kinds of situations lies in the contract.
usually these kinds of contracts require the vendor to maintain parts/supplies for N years, where N is usually 10 or 20 years.
so, the vendor needs to :
initially buy the replacement hammers (essentially the makings of several additional units)
it needs to store them somewhere, along with every other item, including trailers and those big shipping containers
it needs to track the quantities (likely auditing at least a portion of them yearly) and report stock levels back to the sourcing agency
it needs to maintain the staffing to deal with potential requests.
it needs to do [maintence, cleaning, upkeep] to the facility, and pay the utilities and taxes.
all so that if some 19 year old kid drops an 8" adjustable wrench and is too lazy to pick it up and put it back, and someone later notices it is gone, and requests a replacement.
all this because the sourcing agency doesn't trust their own people to maintain the reserve stock, for whatever reason.