Defeat the Golem and collect $1000, but do not enter the city he was guarding. Instead, return to the king and save the game. Reset the NES, reload the game, return to the Golem, defeat it again, and take the $1000. Save and repeat to get as much money needed.
Hint/Cheat by http://www.gamewinners.com/nes/DragonWarrior.htm
Universal Game Hint 