Complete the "Mister Walpole, I presume?" mission during Sequence 2 Memory 3. Pause game play while not in a mission, select "Progress Tracker", and choose "Sequence 2, Memory 3". Replay the mission and continue until you are given the optional objective to pickpocket three Templars. Pickpocket them to get at least 750 Reales. Immediately pause game play, select "Reload", and reload the game from the last checkpoint. You can now pickpocket the Templars again. Repeat the process until you collect at least 100,000 Reales.