In the question.
The question isn't where, it's when. And the answer as far as I know is "not yet" 
JMO/YMMV: My guess is that with Model B still selling out, the RasPi Foundation and distributors don't see any reason to complicate their lives by managing inventory for two products. It's risky having two different builds, because if the more popular one sells out you're stuck with unsold inventory of the other one. OTOH, if someone wants to buy and resell thousands of Model As, the picture could change.
Out of curiosity, any particular reason you want a Model A?
Just to say I have one! 
+ for a robot that I am building that has limited power supply.
This is not any kind of Space worthy robot. 
It will just be a little car that can be controlled through GPIO. It was just a side project that I thought would be interesting to build.
From little Acorns.... 
From little Acorns....
