Reader request: Frugal tips for trip to Hawaii

One of our fellow blog readers has an opportunity to go to Hawaii for the wedding of a friend. She is looking to make it as frugal a trip as possible. Please share your suggestions to help her save money in Hawaii and have a great time! I have never been to Hawaii but have heard that everything is very expensive. Here is her question:

"My sister presented a potential trip to Hawaii for a wedding of a friend of ours. I would like to make that happen. The wedding is July 7th. We were thinking of flying out June 30th and flying back July 7th. Do you have any suggestions for making this trip cheaper? I've read about the entertainment book for Hawaii. Just wondering how valuable that book would be since we will only be there one week.  Any suggestions you have for making this trip as cheap as possible would be greatly appreciated."

I read recently that using an agent for booking travel to some destinations is less expensive with the right package deal, than trying to book yourself. If you have a recommendation for a travel agent, please share that information, as well.

Thanks in advance for any help you can offer her!