http://forum.naruto.oasgames.com/en/forum.php?mod=viewthread&tid=2566&fromuid=20658
This thread will lead you to one instance for 64+ players and yields about 10k in coins per manual try.

http://forum.naruto.oasgames.com/en/forum.php?mod=viewthread&tid=1496&fromuid=20658

If you're not that high in level, view this thread to obtain ~8k coins per manual run.

Peace for now! :victory: