I suggest you write up a plan and budget, then see if it's worth it.
We're currently planning a trip to Oahu this Feb, so some rough numbers might help you.
Airfare - ~600/pp
Snorkeling - ~25-50/pp/trip
Beach chairs - ~50 for 2 chairs & umbrella/day or $10/hr. Buying them at Walmart and giving them to someone on your last day is cheaper.
Meals - I was chatting with a woman the other day - she said her son was in Honolulu, and it was cheaper for her to buy non-perishables in the SFBay area and ship them to Hawaii than it was for him to buy them locally. She mentioned $10/lb for butter. Looking at menus online, restaurant pricing seems about the same as Bay Area pricing (which, IMO, makes WDW pricing look normal.) I'm budgeting ~$100-$150/day in food for 3, figuring a mix of groceries for the room, food trucks and sushi/poke.
Pearl Harbor tour - $55/pp for the Pearl Harbor passport - you can pick and choose which tours you'd like, and I've seen packages for three times this much.
Rental car - we're going to uber/taxi/shuttles or do one-day rentals, in part because of the daily parking fee at our hotel - depending on your parking arrangements, a rental may be less expensive for you.
Hmmm i only intended to copy the part about 55 dollars/pp for a Pearl harbor tour--if you have a rental car DO NOT PAY THIS . All that buys you is transportation. Admission to the Pearl Harbor memorial and Punchbowl Cemetary ofthe Pacifc which are the two premier sites onthosetours is free-the tour company might get to pull tickets for the film and boat to the memorial early but if you get there when they open at 7 you will get one of the early groups any way.
As others have said do good research and be selective when you go. Air fare will vary greatly depending on the time of year-we went last in 2011 and paid 365pp from Denver for travel the first week of Nov-same flight in march as 1200 and in july 950. rental car are cheap-but fall of 11 gas was 4.22/gal. Local food is reasonable-if you know where to find it-its also heavy on protien and starch. fresh fruit, and seafood are good options as long as you have transportation. If you are going to snorkel off the beach not off a boat-rent gear for a week and keep it in the trunk of your rental car -way cheaper than a snorkel tour although i can not give you a fair comparison since we get ours from MWR on joint base pearl/hickam. We never rent or by chairs-dont see them much except at high end resorts. Get reed mats for a couple of bucks at an ABC store and leave them when you fly home.