the instructions are there, of course. try the description at suikosource (http://suikosource.com/games/gs2/secrets/)
Steal From Hans Step 1. Have enough money to buy one piece of armor but not 2 of that armor. Go to Hans (your castle's armor shop) with 1 character wearing this piece of armor, and 1 character with no armor.
Step 2. Buy the armor. Select the character wearing the armor. When given a choice to put your current armor in the bag or exhange for potch, choose either one. At the confirmation screen, hit cancel twice. You will still be in the buy mode, ready to select who to buy it for.
Step 3. Now select the character who has no armor. Select "yes' at the confirmation screen. Now, select that character again, and choose "Put armor in bag." Now cancel out of all the menus. You should have 999999 potch. --- suikosource.com - Your Source for Suikoden