I'm only guessing but you'll be looking at anywhere between
$3500 - $7000 US depending on how many on the hunt / which outfitter and where their concession is. There is a number of outfitters that advertise or are members of this forum. From what I have seen and heard, most (if not all) run a good professional "outfit". I am lucky in that I have permission from several traditional landowners across the north eastern part of the NT and I maintain a good relationship with them.

cheers