I’m a Maui native and it is not that expensive! You just need to do it the smart way, avoid tourist traps and ABC stores, stop at Costco to stock up on supplies before you reach your hotel. Many of the best things Hawaii has to offer are free: beaches, sunsets, hikes, snorkeling, walking the streets of small beach towns. Condos are also way cheaper than hotels and they are usually beachfront.
Other factors, such as surface transport facilities and onward connections, will also affect the relative appeal of different airports and some long distance flights may need to operate from the one with the longest runway. For example, LaGuardia Airport is the preferred airport for most of Manhattan due to its proximity, while long-distance routes must use John F. Kennedy International Airport's longer runways.
Since airline reservation requests are often made by city-pair (such as "show me flights from Chicago to Düsseldorf"), an airline that can codeshare with another airline for a variety of routes might be able to be listed as indeed offering a Chicago–Düsseldorf flight. The passenger is advised however, that airline no. 1 operates the flight from say Chicago to Amsterdam, and airline no. 2 operates the continuing flight (on a different airplane, sometimes from another terminal) to Düsseldorf. Thus the primary rationale for code sharing is to expand one's service offerings in city-pair terms to increase sales.