Your percent of selling consecutively is "correct" but the chance of selling a certain piece is about 17% not counting class items? I don't think math proves this. With at the same time I feel bungie would be smart enough, no matter how much some hate them, to change the item being sold. EDIT: not taking into thought weighted effect maybe in there. I just feel bungie is smarter then this. And I think being able to on Playstation set time back a year before the game launched and still see items from Xur? I don't think bungie was setting up weekly items from Xur a year before launch.