They come in a 1.6, 1.8 and a 1.8t but very rare. there was a girl selling her white 1.8t a few months back. Hard to find, my advice, buy a regular coloured A3 and respray it, the factory audi white, is like an off white.. its not as bright as the new ones.
Is this an imposter or is it really you stranger???
Also on a seperate note, if you have a look at the sticky at the top of this page of A3/S3 pics, you will see a guy in Australia i think with a factory white S3......it looks BOOOOOOOTIFUL!!!