These three trophies are all connected to how much you "currently" have, not how much you've gained and spent. The higher the value, the harder it is to get at first. Best chance to get this early on would be from hoarding everything, but I managed to get this by as early as in China going after General Tsao. Most of the guards have a chance to carry either gems or gold, and they sell very well. If you wait until later, the next episode actually offers a much greater chance to gain loot, though with a bit more work.