Specialist fruit and nut tree nurseries:

Birdwood NurseryLocated near Nambour, QLD. Birdwood is a wholesale nursery, but sells to the public at the Qld Garden Expo in Nambour in July.  Their plants can be purchased at many local retail nurseries.
Daleys Fruit Tree NurseryLocated in Kyogle, NSW. The number of fruit trees for sale is quite comprehensive. As well, this site is also a great place to get information about the plants or post questions to its very active forum.
Forbidden FruitsLocated in Mullumbimby, NSW. This nursery carries a great selection of plants, including rare ones. Forbidden Fruits also attends the BOGI Fair, Qld Garden Expo at Nambour in July, Herb Awareness Day.
Nursery and Garden Industry QldFind a nursery member based on region.