I think they started a fresh printing run on AA in preparation for AC. I've seen a lot more copies on the shelves as of late. Which is why I acquired one for myself.
As for Nier, blame the people that didn't buy it. Damn you people, I hope you're happy. Cavia finally gets everything right and you ignore it in favor of FFXIII. Furthermore, damn you Square, how could you do this? You guys are dicks.