Be sure you understand all of the fees and insurance requirements of Hawaii for renting a car.
I had a good deal, compared to cars in the 48, and when all of the fees (tourist tax, pineapple fee, once in a lifetime fee, etc.) were applied, including some line where if I didn't take their insurance, I couldn't have the car (mine was not enough), the car was about double the reservation price.
Just understand what they are quoting you. I think there are more fees and taxes in Hawaii then anywhere else in the world I have travelled.
But renting a car is still the best bet. Aulani & Ko Olina is a long way from everything.