Thank you for posting this (I was going to post the same notice)! I just discovered this myself (and I, like you, had already purchased all the other DLC). I saw it a few days ago, but was content with what I've already unlocked from just playing the game, so I had largely ignored the last item. Then I looked closely at the ad, and seeing it said "Save 1200 points..." I was curious just how low it was. I was "SHOCKED" to see it was absolutely FREE!
Keep in mind, that the last item is ONLY free... if you have already purchased the previous offers!!