Having said that there are people who only buy automatics - I'd be prepared for a bit of a wait though. Personally, I don't know anyone who would favour an auto over a manual for a car like a Focus.
It's unlikely that someone will specifically want a ford focus, espcially as there is value to be had in better makes.
I would emphasise the AUTO and engine SIZE (I assume it's a small to medium car) in you add's. Word it this way on buyandsell, donedeal and gumtree. In my view a local paper ad, is the only one worth paying for in especially if your regional, as some people dont want to travel far when buying a used car.
TBH I find the automatic gorgeous to drive! I never had any interest in them before I actually drove one.
I think I'll ammend the ads to stress the automatic nature of the car - there are soooo many of it for sale that at least it differentiates it from the others for sale.