Having personally moved from California to Hawaii several years ago, and also having helped many others make the move across the ocean, I know what it takes. It's not easy, but if you know what to expect, your move to paradise can be a lot less stressful than you think it might be. This is a 7 step guide, so read along and don't be afraid to contact me if you have questions, especially if you plan to buy a house anywhere on Oahu.
Step 1 in moving to Hawaii - figure out if you can afford it. Of course you will want to see how much Honolulu homes are, so use my property search to see if you are even in the ballpark. Hawaii is one of the most expensive places on Earth to live! Remember though, property taxes in Oahu are quite low, so while the prices seem high, your monthly payments could be a lot lower than you would think, especially if you've come from Texas, New York, or California. You will probably pay around $700k-$1mil for a house, but your property taxes will be about $150-$200 per month.
Hawaii is particularly expensive if you live in East Oahu, where real estate prices are even higher than the rest of Oahu. I'm talking about Hawaii Kai, Diamond Head, Kahala, Aina Haina, Kailua, and Kaneohe. These are very nice areas, and you get what you pay for. While you can still expect to pay $7~$9 for a gallon of milk at Foodland or Safeway, now that we have 4 Costcos on Oahu, prices have come down a bit for most things. Surprisingly, gas prices are about the same as California a lot of the time.
Of the thousands of people who move to Hawaii every year, one thing that is on the mind of every one of them is probably the difference in the cost of living. But we don't usually use our AC, we never have a heating bill, and we wear a lot less clothing. I own 1 jacket, I think. You will save money just by not trying to compete with everyone on how they dress and the car they drive. If anything, a lot of people will look down on you if you are too showy here. Some of the richest people in Hawaii wear T-shirts and board shorts every day and drive a pickup truck (like me.)
But what about other expenses? Just assume everything will cost 10-20% more, except for used cars. For some reason we have too many cars here and used car prices are sometimes lower than many areas of the US mainland, especially if someone is moving off island and they need to sell their car quickly.
Bottom line is - if you want to live here, you might have to change your lifestyle a little bit, but it's worth every penny.