I have not been able to verify this, but its being said that the Tau codex is no longer available to retailers. I am assuming that means independents, but its also mentioned that there are several models that are also no longer available.
via MachineSlave on Warseer
Tau codex no longer available to retailers
Just stopped in my local nerd store to get some what-nots and the lad in charge of orders said that the Tau codex is no longer available as well as the Hammerhead, crisis suit and one other unit (I forget which one). He said when that happens to a codex "it is just a few weeks out, so expect to see it by April." This was some good news to me!