Well, the upper bounds on this has to be 4 turns right? You can buy out the entire supply in 3, so instead of buying everything, just buy all the Catapult/Rocks, and a couple Ambassadors. The next turn King the Ambassadors to send them all back in the required order.
Edit: probably you can gain them and send them back on turn 3 by adjusting the turn 3 craziness bit.