Current Gas Prices in Hawaii
December 22, 2008 – $2.40 a gallon!! I heard Costco on Oahu has gas under $2.00 for the first time since they opened in the 90s! crazy! It was really fun watching the gas prices fall like a brick .. . and even more fun filling up at $40 for a full tank instead of $70 
September 8th, 08 – prices held at $4.48 a gallon for a month but are now falling slowly. Today, I filled up at $4.35.
July 1, 08 – prices go up a few cents every day it seems. Here in Hilo we are sitting at $4.48 a gallon for the cheapest.
I live on the Big Island and will try to remember to post the current gas price here every time I fill my tank. Prices on Oahu will normally be a few pennies less than on the Big Island. Prices on Maui and Kauai will normally be a bit more, while prices for gas on Lanai and Molokai could be up to $.50 more.
Just as a historical reference so you can compare prices with wherever you are from, I think I remember prices hovering around $2.00 a gallon in 1998. Prices of $2.70 were normal between September 11th and Hurricane Katrina, and after Katrina, the highest price I remember is $3.70ish a gallon.
December 10th, 2007: $3.35 a gallon – well, just before thanksgiving prices shot up to here and they are holding steady.
September 18th, 2007: $3.17 a gallon – OK, summer prices are coming down slowly.
June 12th, 2007: $3.40 a gallon 
Prices were fine until about April, and then WHAM, they’ve been sitting at 3.40 for a while now.
December 20th, 2006: $2.909 a gallon
November 5th, 2006: $2.959 a gallon (wow!)
October 21st, 2006: $3.059 a gallon (lowest I’ve seen in a long time)