Approximately 1,506,000 Purple Hearts were produced for the war effort with production reaching its peak as the Armed Services geared up for the invasion of Japan... it wasn't until 2000 that new ones were ordered, and that was just because they had lost about half of them.
The death toll on the US side would have been staggering. The death toll of Japanese military and civilians would have been even more horrific. Not using the bomb was never even an option. If Truman had the weapon that could have prevented the deaths of countless millions - and didn't use it - well, that's why not using it wasn't an option.
No one has mentioned the Russians at the boarder knocking at Japan's door, either -- and Stalin had big plans for Japan in post-war Asian/Pacific theater. This weighed heavily on Truman and his staff -- as well as the Japanese themselves. Some historians note that it was the threat of the Russians that made them sue for peace, not the A-Bombs.Also note, the firebombings using incendiary bombs were much worse than the A-bombs... and the Allies only stopped because they had run out of them