They will be released next year.
3 out of 4 are available at retail.
I bought all four.
Retail MSRP is $30 each
They are still slated for an October release, but with the standard CMoN delays + Chinese new year, early next year is probably a good estimate. They were originally supposed to be released in June, but got pushed back so that they could completely revamp the entire system for them (which is mostly the reason that Inferno has been delayed so long too).
In the end, it will be better since now they will all feel different from each other instead of being cookie cutter fights with different elemental dragons. We just hate the wait, lol.