The Amazon page finally looks like you'd expect it to, with books in stock and no bizarre ETA.
There's also a used copy available from the UK (?), and a new copy that ships from Japan (??), along with several from various parts of the US.
Apparently some online sellers have an arrangement to get discounted books right away, so they can sell them for slightly cheaper prices.
Except for the copy from Japan, which costs almost three times as much.