Go through your results for flights to Hilo in USA with Netflights. Although United Airlines usually has the best prices, it's best to double check what's available for your travel dates.
If you don’t have set dates for when you want to fly to Hilo, try searching by month – that way, you can compare airfares throughout the year.
So, if the flights to Hilo don't work for you, you could always try searching for flights to other airports in USA.
For even more options, check what other airports you could fly to Hilo from. You might be able to make a saving by going from a different airport or city.