The Justice Badge Quest is located in Windurst and require 1 rabab tail and 4 onions to complete. You can buy a stack of rabab tail in the auction house for 50-100 gil. In the docks of Winhurst you will find an NPC that you can give the rabab tail to. In exchange he will give you the Justice Badge. The Badge sells for 500-2000 Gil in the auction house. Once you get the badge, give him 4 wild onions and you’ll receive a scroll that sells up to 5k gil in the auction house. Again you can repeat this quest by creating a mule character and transfering 1k gil. This should be a very easy and fast quest to do.