TIP - If negotiating for a trip it is often cheaper to bargain for the whole vehicle and get a few friends to join you.
On our recent South Pacific cruise we docked on the island of Lugainville. On the dock locals were waiting with their vehicles, small cars, mini buses and trucks. Most wanted to charge a fixed price per person depending where you wanted to go. We tried a different tactic and negotiated for a truck to take us to the Blue Hole and Million Dollar Point for $100.