Hawaiianair.com has it for $357.70 right now. (4/9-4/16 LAX-HNL) May only be a few seats remaining.

Both Expedia and Travelocity just turned up a $392 fare for me (also 4/9-4/16 LAX-HNL).

You can try the Hawaii-based Panda Travel. I've used them quite a bit and their customer service by phone is remarkable - short wait times and very competent and helpful staff. PS: BTW I don't work for them.

I did a search 4/9-4/16 LAX-HNL on Panda Travel and it returned 2 DL fares @ $411.09, 1 HA fare @ $509.20 and some other more expensive fares. Good luck!