Economic in terms of, munitions, fighter planes, and tanks cost, and whether or not the use of the bomb was to stop them spending to much money on these things. Also the drain of manpower having so many people in the army and not spending in a capitalist country. this does not include the cost of creating the two bombs. As in the use of the atomic bombs in the war, as a weapon against Japan and a way to win the war faster, and prevent damage to the American economy.
Edit: clarification
From the way you phrased your question, I assume you're asking about the use of atomic bombs in Hiroshima and Nagasaki, but just to clarify: are you referring to the use of atomic bombs against Japan or America's adoption of a nuclear arsenal after the war?