You are absolutely correct with your cap rate quote. Currently there aren't TONS of these types of properties, but there are some. However, if you are in the market to purchase one, be prepared to pay cash and make sure you have an agent that understands cap rates and how to calculate ROI.
You will find that rents tend to be lower in relation to sales prices in Honolulu. That is, it takes longer to recoup your investment in the multiunit market. However, you will also find that our inventory is extremely low now, so the demand for all properties has built up over the last few years.