So, ive noticed a lot of people have had issues buying TTK and the collectors edition extras even if they own the full Year 1 on a single account. Im a similar person who had that predicament (i owned the Y1 expansions via a season pass i got with the vanilla game preorder). However, i found a fix that worked for me on XboxOne (might also work for the other platforms, if people could confirm one way or another ill update it.) Rather than going into the Xbox marketplace on console or your PC, go into the destiny game itself and open your destination map. Over to the right there will be the TTK content locked off with an icon. Cursor over that icon and youll be given the button for "more info" if you bring this up it will show you the option to purchase TTK upgrade or TTKUpgrade+Collectors edition digital content. Pressing purchase on either completely goes past the Xbox marketplace and straight into the checkout sequence (choosing your payment option and such) which allowed me to get past this annoying issue. Hope this helps anyone who had/is having a similar problem.