If packing for Hawaii and staying within a set budget is a main issue, try to pack light, and buy when you get there. Pack one swimsuit, three days of clothing (shorts and shirts) and cameras. The rest you can get at WalmMart and Sam's Club (located next to each other) the first full day there.

Particularly if you live in a cold area, arriving in 80 degree weather and hauling around heavy luggage within an hour of sitting for many hours already may not be on your list. You have to get to the luggage area, drag over to your shuttle pick up, get the rental car and pack that. If you are going to a hotel wihtout a rental car, you have to wait for the shuttle to fill up, as long as 45 minutes. When you pack so little, you can move around very quickly.

At Walmart you can buy cases of water, snacks, sunscreen SPF80+, towels, chairs, sandals, umbrellas and coolers. Most of this is only a few dollars and comes in many more styles than you can find back on the mainland. Do not forget the sand toys! You can get a stryofoam surf board for kids that has a plastic see-thru window. It's great for snorkeling without getting your head underwater.

If you are not the type of person that likes to buy things and then leave them to be thrown away in the trash, then renting equipment is a good idea. There are places in Waikiki and the North Shore, and Kailua  that you can rent from and most of time everything can be delivered directly to you. Excess luggage fees have been crazy lately so it makes sense to pack light and rent equipment on Oahu.