Go to Oakvale and buy every emerald in the shop. Look at the next delivery and sleep for the amount of time needed for the store to restock. Keep doing this until you have 90 emeralds. Note: Make sure to buy all the emeralds in stock at once, so that you can buy them for fewer gold pieces. After you have 90 emeralds, sell them to the shop, then buy them back. You should be able to sell them again for much more than you bought them for. It is possible to get 1,000,000 gold pieces in ten minutes. This also gives you a lot of skill.