Forty five more gold pieces:
Obtain the sword from the fortune teller during the first scene. Press Pause(73) on controller two to collect more gold.
Press 1, 1, 2, 2, 1 + 2 when the level and stage numbers are displayed.
Level select (Japanese version):
Hold 1 + 2 + D-pad button and power on the Master System console.
Level select (European version):
Press Down + Start at the title screen for a level select feature. Press Up to select a new starting level.