Boost Mobile came up with a $35 unlimited calling plan for its Hawaiian subscribers.
Why is the price so low, you ask? Simple, the calling area was limited to the user's home-area, i.e. Hawaiian Islands. Thus, if you leave the home-area, you'll be charged $0.15 per minute. :)
Additionally, unlimited SMS, unlimited data, and coverage in California and Las Vegas will cost you $5 each.