This trick can be used at any point in the game. Save the game near a shop. Drop all your expensive items, then load your saved character to the same location. After the loading screen, pick up all your items and sell them. Do this again in the exact same order. You will get a lot of money. Also, use the "Duplicate items" trick with your most expensive item or weapon. Keep duplicating it until you cannot hold anymore. Sell the duplicates and buy the most expensive weapon you can afford. Duplicate these even more expensive weapons and sell them back. Keep doing this to build an unlimited amount of gold. It gets easier when you can afford the more expensive weapons.