KBS2's "Entertainment Weekly" broadcasted on November 17th revealed how much money top idols can earn from each event they participate.
It was revealed that A class idols can earn from 40 million won~60 million won per event participated. Other idols normally can make up to 20 million won per event.
On the other hand, it was also revealed that the money is splitted equally among the members who participated in the event, one member won't be able to receive it if he/she was absent from the event.
source:nate