The only known purple fish is this fish...
Keep in mind this article was posted in 2003.... I have yet to see an update on Stark's experiments or heard of any other purples being produced. It's possible some people are still working on it and not letting any fish get out of their fish rooms but more likely it is proving to be extremely difficult to breed true.
As for LPS fish. Your just not going to be able to tell what you'll get. I'm not sure how it works in Australia but fish bred from LPS stock tend to be unpopular and red/blue mixes even more so.... that is, at least, for serious breeders. People looking for just pets tend to care less about the genetic make up of their pets.