Dave, you could get something made locally that replicates look, but is slightly smaller. That way, at least when mobile, it would attract little, if any, attention. However, when stationary it would be another matter...
Black max advised in '05 in NSW "there is 2 fines and depends on how nice the cop is - The one I got was drive vehicle with illegal numberplate - No points lost but a $78 fine - the 2nd option is about $980 and 3 points for obstruct or obscure numberplate"
http://www.aus-cartalk.com/forum/viewto ... highlight=Bruce mentions in '06 that in Vic the fine had gone upto $130 at some point.
If you're still interested then try the following as they're quoted as having supplied stickers in '06: SCOTCH-LINE CENTRE P/L, Unit 30 / 148 Chesterville Rd Moorabbin (03) 9532 0660