Hi Eric,
The Visa was no big deal to pick up in the Airport at Port Moresby, they charge $100 kina which I believe is around $40 U.S. But you need to have the Kina so change some before arriving. Their currency exchange is on the other side of customs so you can't get to it until you're through. It seemed most of the people on the Plane were residents or not in need of one as only 4 or 5 people lined up at the booth to buy one at customs/immigration.
Depending on where you are going, I might have some additional tips for you. Talked with a lot of people there about the different types of diving etc.
Also, I got nicked $100 AU for the Air Niugini flight from Cairns to Hoskins. They weighed my carry on and said it couldn't go on the plane in the main cabin, it was too heavy. I was too tired to argue at the time. But I'd come prepared for that and had bought a hard sided carryon on the off chance I'd have to check it.
Now, on the trip back, from Hoskins to Port Moresby, they weighed all my luggage at once. Said I was over and charged me $70 kina. Maybe $30 U.S. (Strangely, or maybe not, the payment was quickly put in his pants pocket). Again, only Kina accepted so I was glad I'd converted in Australia. Another odd thing, I understood there was supposed to be a $30 Kina departure tax. But no one ever mentioned it so not sure what the deal is there.
Once in Port Moresby for the return to Cairns, I was told my carry on was too heavy again and they wanted $100 AU. I told the agent that I was a diver and the suitcase was full of Underwater Camera gear and it was very sensitive. She had me wait and talked to a supervisor, came back and said no charge for the extra bag. So, again, it helped to bring up being a diver/photographer.
Finally, when returned to Australia, I had $150 in Kina to exchange. The currency desk said they were out of US dollars but to try exchanging it when I transferred planes in Sydney. My plane out was delayed to the point that I had just enough time to make connections and no time to exchange the Kina. When I got to L.A. the currency exchange said they had no conversion rates for Kina and couldn't take it. So, I've got a reason to go back. LOL!
If you're going to Walindi, I have some very specific info for you that might be of help as well.
Rand