Extra money in Rogue Valley level
After meeting the prospector, he will lead you to a cave with two villains. After killing them, the prospector runs outside only to be shot by two snipers. If you kill the snipers before they kill the prospector, he will drop a money bag worth $1,500. To save him from dying, kill the villains in the cave, then run outside before the prospector can and kill the snipers very quickly.