In the "Tomb of the King" level where you get a sword, shield, and armor. Just get the sword and shield and do not pick up the armor. Then you can exit to the main menu and go to the vendor, sell the sword/shield for about $1500, then continue game. You can repeat this as many times as you want. Just make sure you don't accidentally pick up the armor or it will trigger a new checkpoint and you can't repeat it. It only takes about 1.5 minutes each time because the checkpoint is right near where you need to be.