Hawaii can be done cheaply - I do it. It really depends on your overall budget. For example - I just checked flights in February for a week - early Feb, and flying into Cancun was under $400 pp, whereas Hawaii is almost double that - longer flight, and time zone change as well. If you chose Mexico, you wouldn't need a rental car, but in Hawaii you would need a rental car for every island except Oahu. Food is also much more expensive in Hawaii but you can reduce that by staying in a condo and preparing at least some of your meals - I usually have breakfast at my condo, pack a lunch for the beach or days adventure and then dinner out, which helps.
While I love Hawaii, I also love Mexico and it does offer a better bargain. My favorite spot is Isla Mujeres - a beautiful small island near Cancun. Gorgeous beaches and water, great food and all types of lodging for every budget. Just depends what you really want to see and do, and again, what the overall budget is. Good luck! :)