Most folks agree that you would do best renting a car, especially if you are a DVC member and won't have to pay the $35/day parking fee.
That shuttle fee quoted you is a per person price, so keep that in mind when doing the math. Aulani is about 45 minutes from HNL, without any traffic. Be aware that HNL is a very large city and you will want to avoid rush hour traffic if at all possible.
And BTW, Aulani is spectacular! You will love it!