Or not enough since the job was not done

No, he paid so much that everyone thought they'd make money and not do the killing themselves. Had he offered say, $30k, the killer would not have outsourced it.

…and the job might have been done (might because the first person in the chain may never have intended to do the killing himself. The intermediates may just be brokers needed to move from the circles of rich Chinese to the circles of killers)

Of course, offering too much also runs the risk of “Chinese Whispers” (https://en.wikipedia.org/wiki/Chinese_whispers) the initial message “Foo will pay $X to kill bar” could end up as “bar will pay $x to kill Foo”.