These are goodies which, due to oversupply or a poorly timed peace, are sold off (often at reduced prices) by the military.
Many towns have a store that specializes in selling military surplus goods (an "Army-Navy Store"). These stores are full of olive drab goodies: tents, boots, rocket boxes, duffel bags, you name it. A great place to go for camping gear.
Some places in the world have even cooler stores where you can buy surplus guns, ammunition, and tanks.