If looking at the room rate alone, I am confident you will have a better deal renting DVC points than booking direclty with Aulani or via Costco. Plus, if you stay on points, parking is free otherwise it is $37/day.
If you include airfare, then it is worth evaluating the package price via Costco Travel (as the pp said, you don't have to be a member to price out a vacation). We are going to Mexico this winter instead of Hawaii and we saved over $150 per person by including airfare in the package vs. pricing out the airfare directly on the airline's website. The resort price was a small savings. Combined with the Costco cash card, we are saving about $1k booking with Costco Travel rather than separately on our own. Last fall, the Aulani Costco packages reflected the same promo Aulani was offering (I think it was like up to 30% off stays of 5 nights or more) and then the Costco package added on a daily meal at Ulu cafe. It was a better deal to book the hotel and rental car package through Costco Travel than through Aulani. All that said, if we had been able to rent points, it would have been a greater savings (all DVC rooms were gone for the week we needed to go).