PNG Airline discounts, any tips, ideas?

Hi
Do you have any advise about PNG airlines? (they are so expensive.. so im looking for any tips, links, experience of someone, etc.)
Is there any discount for multiply trips in PNG?
group discount? (we are 7 people)
Is it much more expensive to rent a small airplane instead of going with scheduled airline?
Any tips, tricks, advice in this topic?
Thanks a lot
Gabor

you need to speak to a good travel agent

chartering a plane is very expensive - not really feasible unless you are mine/oil company