To get lots of money, go to the island and the guard asks you
for the silver coin. Give it to him and then find the shop.
Give Heimdall all of your gold, and the adamantine axe. Sell
the axe, and confirm the sale, then sell it again, charging
as much as you like.
If you haven't got enough keys of objects go to an island that
has an object you need more of. Take an object from the chest.
Leave the island and save the game. When you reload the game go
back to the island and the objects have miraculously reappeared.