The $100/yr is often seen on Big Island ag-zoned parcels with a dedication to grazing. The option you mentioned would certainly work if you came across that situation. If you buy a single large parcel, you can have a portion of the acreage dedicated and that portion would be taxed at a lower rate than the portion upon which your residence and/or any additional farm dwellings sit. You can find all of this on line at the Hawaii Property Tax website (you are looking in Paauilo, then it is the County of Hawaii's tax code that would be of interest. Unlike on the Mainland where Dan who answered first is describing, it is the county rather than the "town" office. ) Of course your residential rate will also depend on whether this would be your primary residence or a second home.
The key to low taxes is putting it into farm and open space (or whatever program they have there) That gives the low tax base. Homestead exemption and so on.
Ask at your local town office what the best way is to reduce taxes on a farm. They know how it works and will explain it. I expect taxes to be over $100 a year, but maybe you will surprise me and come in under that amount.
