U earn the gun by buying the game spending money on the game and playing it. Iv got over 100 hours on destiny I waited a whole year to get the hawkmoon. I got a green engram and got a monte I did a heroic strike and got a exotic engram and no I didn't have the 3 coins on and I got a year 2 hawkmoon so yes I earned mine. Of u buy from xur then u still earn ot because u played the game and earned the strange coins