There are great training courses on the mainland, but of course they also have deserts and wooded areas that accommodate live fire training. In Hawaii, that just isn't readily available.
Maybe $300 for a course in Hawaii is a "rip off," or maybe it's the high cost of doing business in an anti-gun, over taxed. litigation-happy Socialist run state? I don't blame the course provider for the environment that's unfriendly to business and 2A. It is what it is.
I tend to look for the best I can afford. Front Sight, while not local, was very affordable. $200 for the membership plus $50 for the background check. That included a 5-day defensive handgun course and the CCW training, fingerprinting and notarizations needed for up to 4 permits -- AZ, NV, UT and FL. Ammo cost is what it is no matter where you train. Some places are cheaper than others, so shop around. I spent $225 on 1,000 rds Fiocchi 124gr 9mm ammo for the course at a local ammo store there. I shot all but 80 rounds. If I lived in Vegas or nearby, I'd be taking Front Sight training a few times a year.
Travel was incidental. I used my frequent flier miles for a free roundtrip ticket, and I stayed in Vegas in a comp'ed hotel room. I paid for a rental car and the gas to travel to the training site every day. After being on a gridlocked island, driving for an hour on open highway is relaxing!
The local course might have been more convenient and a few bucks cheaper, but the whole experience with a large group of well-trained instructors, the variety of training scenarios, and the constant attention to safety was well worth it. Not to mention I also won $2,500 playing blackjack!
I'd look at my financial resources, vacations I might want to take, and training opportunities along the way. You might be able to do better than limiting yourself to Oahu courses.
Just my own personal experience and opinion.