I was searching through the furniture folder in the images folder, about to do some modding and I came across some clothes hampers and a few variations on the bighearts poster. None of these items show up in my store for purchase. Is this a bug or were they left out of the final game but not removed from the images folder? I'm quite curious.

It's possible that they were left out of the final game. There are definitely some items in the Images folders for previous games that weren't implemented in the game.