Other than the Oboro mode cheat to get easy money, there is a mode that is easier (but slightly longer) way to get money. Set the Attack power to max (4), and set the handicap setting to "Chakra Max". Set the live amount to 1. Play as either Zabuza, Orochimaru, or Kakashi (Sharingan or not. It doesn't matter.). If Zabuza or Orochimaru, fight Sakura. If Kakashi
or Sharingan Kakashi, fight Naruto. If you're Zabuza or Orochimaru, click the X button as soon as you're in range. Sakura will die. If you're Kakashi, use the X attack immediately. Fully cahrge it, and Naruto will die. Killing your opponent 100 times will get you 20k.