Sometimes Steam is just bad at maths. It pays to pay attention.
Notice something odd about the bundle price?
(I did end up buying the game, but not the guide — this was just for illustrative purposes. Haven’t played it yet, but I might eventually get around to posting some comments on it.)
Thus far, I’ve managed to resist the Sale fairly well, but Steam does still have a magical ability to make me throw money at them. (Despite their obvious failure at maths.) Sigh.