Not staying at Aulani, but staying next door at the Marriott Ko'olina...same airport
We purchased our airfare back in June with Alaska Airlines.
Total for all 5 of us was just around $2600 roundtrip out of Bellingham, WA.
For the past several months the price has gone down. The great thing about Alaska Airlines is, if you check and the price is lower they credit you that amount. There is no limit on how many times you can do this.
To date, I have been credited $419 on those flights, that's enough for another round trip ticket. I log on weekly to my reservation and "submit a claim", it will tell me if the price has gone down or if I already have the lowest price.
Another tip I learned, is to enable "private" browsing on your internet browser. This blocks all cookies and identifying information so it treats you as a new shopper. If you keep frequenting the same travel websites for the same flights, chances are you will get the same prices. Try searching in private mode to see if that changes things.