There is a shopping shuttle that runs Tuesday, Thursday and Saturday. It leaves at 8:30 and returns at 5:30 and goes to Aka Moana, DFs Galleria and Waikele Center.
This was sent to me on another thread. I believe the cost is $30 per person.
I haven't used the shuttle, but we're going in April and don't plan to rent a car for the 4 days we're there, so I may take advantage of it then, especially if DW decides to play golf that day.