New ST's with a discount are rare, Ford really restricted the supply to the likes of broadspeed, there are people still waiting for theirs on STOC who have ordered from broadspeed and the like.Basically Ford would not give these guys any fleet discount like they do with the lesser models.
The only way of getting a new ST discounted is by knowing someone who works for Ford, or being in the army.
If its your own money buy a Golf GTI instead, the ST costs a fair bit to run, lovely car, but too dear to run for what it is.