ACE has had a spotty record over the last couple of years, and in my searches, I have been unable to find anyone that has them in stock.

A lot of people have been opting for the Robbe(futaba) F-14.
It is currently available through http://www.harbormodels.com/

Others that I know modify their own cases and customize their transmitters.
One friend has an old Ammo box that he modified to drive his 1/12-1/9 scale tanks.

The transmitter pictured first below is a modified four channel Futaba transmitter. It is just a matter of coming up with the sticks you want.
The second one is an old Futaba Attack two channel that I rotated the right stick 90 degrees for tank controls.