Actually there are very few new build homes that come on the market, it is more common here to build a home and there are certainly a lot of them being built around the Noarlunga area particularly Seaford.
The FHOG is available for new builds: http://www.revenuesa.sa.gov.au/grant...st-home-owners this thread may also assist http://www.pomsinadelaide.com/forum/...ty-update.html
A broad overview of how it works is that you purchase a block (not plot, lol) of land of which you pay the usual buying costs on ie stamp duty and then source a builder that you wish to use to build the home.
No extra associated buying costs are payable on the build ie stamp duty which of course is a further cost saving (as well as the FHOG if applicable) which is only released when slab is laid.
As said it is very common here and there are loads of display homes/villages you can visit and are able to talk to builders to get an idea yourself of how it all works.
Just to note that although there are cost savings by paying less stamp and grants available over established homes it isn't necessarily going to be a cost saving in total. You have to account for the fact that you will be paying a mortgage on the land and progressive build during construction whilst paying rent and there are a lot of additional costs once underway therefore by the time the house is built and driveways and landscaping etc paid for it may have been cheaper to buy an established house.
Obviously you are getting a brand new home and one designed or picked upon how you want it but it is not necessarily going to be a cheaper option.
Anyway you will be here soon enough and then you can do your own research, we are just about to embark on a build ourselves after having lived in the established home we bought in 2009.
Anyhow whichever way you go there will be many hours spent at weekends visiting open houses or display villages!!! All good fun ....... to begin with anyway, lol :)