I not only have them all, at least one of each actually dropped for me (not Xur purchased). I did purchase my first Thunderlord form Xur, only to have it drop that same night from the exotic chest in VoG. My buddy told me I should buy the gun because it was highly unlikely that it would ever drop for me. I laughed when it dropped the same night, I was a little frustrated, but strange coins are easy enough to come by.