I don't think you need to worry about plant material-perse. Anything that is not on the scheduled substance or prohibited imports list should be fine getting through customs.
When AMT was not on the prohibited imports list I had contacted a Customs Officer from the TGA and asked if it was possible to import alpha-methyl-tryptamine for personal use.
No problems at all. The same goes for a number of herbs not listed on the prohibited imports list. Ordering Sceletium tortuosum was no problem either. It is not currently listed on any prohibited imports list.
There are number of useful and effective herbs that are not very well known that can be imported for personal use. Make sure you do your reading about them all first before going ahead.
With Salvia, technically the chemical that it scheduled is actually the wrong chemical. It was then changed to another chemical name that is still wrong.
Salvinorin A - Source
http://parlinfoweb.aph.gov.au/piweb/view_document.aspx?id=800833&table=HANSARDR
METHYL (2S, 4aR, 6aR, 7R, 9S, 10aS, 10bR)-9-ACETOXY-6a,10b-DIMETHYL-4,10-DIOXO-DODECAHYDRO-2-(3-FURYL)-2H-NAPHTHO[2,1-c]PYRAN-7-CARBOXYLATE
From IUPAC
(2S, 4aR, 6aR, 7R, 9S, 10aS, 10bR)-9-(acetyloxy)-2-(3-furanyl) dodecahydro-6a,10b-dimethyl-4,10-dioxo-2H-naphtho [2,1-c] pyran-7-carboxylic acid
There are a few other names for. Essentially if you wanted to be bothered you could argue a case in court. However this would require an expert witness with information on the compound. There are a few guys working with this compound who could help you out. You could get A.Shulgin down here to help you if you were taken to court. If you do that you will have to tell me so I can get him to sign a book of mine.
L