Beat the game, and after the credits and endscene, an option will appear on the title screen that allows you to change the difficulty. Now, you can choose between Normal and Hard modes.

Beat Normal Mode under 3 hours or just beat Hard Mode.

In the market, there is an orange can. Proceed to kick it behind the counter of the Jet Bakery. A message will say you have received a free 1000 Zennys. Leave the room, and return to have the can reappear. You can do this can many times as possible,Note: later in the game, the amount will be bumped to 2000 zenny each.