Hawaii residents can save money by gardening.
It's no secret that most of the food in Hawaii is more expensive than most locations in the mainland; fortunately, Hawaii's weather is consistently mild, allowing us to pretty much grow most fruits, vegetables and herbs year-round.
Last year I grew 40 bunches of green onions without much effort for less than $5 (premium dirt, seeds and fertilizer). 40 bunches of green onions normally retails for $60-$80 ($1.50-$2 per bunch); in other words, I saved $55-$75 growing my own green onions.
This year I started growing my own lettuce. I estimated that I'm going to grow 24 lettuce heads this year for $5 (premium dirt, seeds and fertilizer). 24 lettuce heads normally retails for $24-$36 ($1-$1.50 per head); in other words, I'm expecting to see a savings of $19-$31 growing my own lettuce this year.
I know some people in Hawaii that grows most of their vegetables and herbs year-round. They grew their own potatoes, tomatoes, lettuce, broccoli, cabbage, carrots, bell peppers, garlic, green onions, chives, oregano, basil, sage, ginger, rosemary and more!
Even people living in an urban location such as Honolulu can plant a decent amount of their vegetables and herbs without much space. Here's a video of a plant expert discussing vegetable and herb growing in an urban location:
I suggest that you purchase "Growing Vegetables in Hawai'i: A How-to Guide for the Gardener" and/or "Growing Fruits in Hawaii Also Herbs, Nuts, and Seeds: A How-To Guide for the Gardener" by Kathy Oshiro. The author of those two books has been growing fruits and vegetables in Hawaii since 1979. She details the altitude, sun exposure, soil, fertilizer, and rainfall needs for dozens of fruits and vegetables.