To get cheap ticket you have to be smart enough to find best deal for you. Below are some steps which will help you to get cheapest ticket for flights 1. Purchasing flights from small airports. 2....
That would depend on the point of departure and the class of service desired.Example: First Class from Christchurch NZ costs more than Coach from Miami.
I don't think any of them really have "cheap airfare" but the islands I have been checking that offer good deals are Puerto Rico and Jamaica. Maybe others here can give you a better answer.
I have good luck finding great deals through Southwest. Usually the vacation package deals, are where you find the great bargains. Booking in a fair amount of time gives you a better deal as well.