a price on one's head

     To have a price on one's head is not just an old saying. Criminals really did have a price put on their heads, just as our government may offer a reward for information leading to the arrest and conviction of the perpetrator of a particular crime. When someone informed on the criminal, he or she was paid a reward--the "price" that was put on the "head". You can search "reward posters" if you want to see some real advertisements promising money for the capture of a criminal.