Don't know about buying fruit trees from these guys (don't really have space for any more / cannot easily transport them ourselves)
What I can say:
* My bottlebrushes from Oderings have been the hardiest + most reliably flowering (i.e. the silvereyes one outside my window)
* My maples are from Bunnings. Doing OK-ish (except mid-late summer). Can't remember about others.
* Mitre10 - Hmm... while they have "1 year plant survival guarantee", TBH most things I got are now dead IIRC