I would suggest mask snorkel fins as the first thing.
Second I would suggest a regulator setup with an spg. I would wait till you get to Hawaii to see what the local dive shops carry and go with one of their brands as they will be able to service your setup easier. While most dive shops can service most regs, it would probably be better if you go to a dive shop that services the brand that you dive with all the time.
Next I would go with a BC. Since you are a new diver, I would suggest trying to rent a few different types, jacket, back inflate and backplate and wing before making your purchase.
A lot of people stress good thermal protection. From my dives in Hawaii, I would think the protection would be nice but not an absolute necessity like diving in the California current. You can always go cheap and get a full wetsuit at the local sporting goods store for waterskiing or surfing. This will get crushed at depth after diving it a few times, but will still act nicely as a 1-2 mm dive skin that should add some comfort. If you find that this is not enough, you can get a nicer one for winter months and keep the crushed one for summer months.
Checkout scubatoys for a wrist mount dive computer. They just had a sale on the oceanic nitrox geo that I purchased for 250. The sale may stil be going on.
If you want to be cheap, you can always get the bc and computer on ebay and a wetsuit where ever. The only thing you want to go to the LDS for is the regulator setup as service will be cheaper if you get it at the store rather than ebay.