You know those strange coins that you get for doing one gold teir public events? You spend strange coins on Xur the [something..gaurdian?] of the Nine's shop. He shows up every 5 days or so and stays for 2 days at a time. Most exotis cost 7 stange coins. 7 days of gold teir public events for one strange coin a day= 7 strange coins a week to trade for an exotic that costs 7