Indonesia to Darwin,Australia
 

I'm looking for a ferry/ship/cargo from anywhere in Indonesia to Darwin in Australia.We are travellers using only "public transport",no car no bike.The cargo shipping company from Timor don't allow paying passenger on board.We found a luxury cargo Singapore to Freemantle,Australia for an horrible 705 GBP one way for 1 person.Anyone know for a cheap way to go in Australia without take the airplane?
Thank you.