Former resident, a couple of trips "back home" ( to me ) recently ....
Yes everything does cost more .. IIRC Hawaii has something like 5-6 container ships a week to bring in stuff from milk, to cigarettes etc.
Being on the Big Island, or Hawaii itself, you can add Vog to your vocabulary:
It affects all islands, but is manageable. Kiluaea is certainly a concern, but a trade off. All the active area is government managed. I'm not sure about trade winds .. most of my time was on Oahu.
Oh yes, if your into gardening your in for a treat.
Agreed on climate control costs, you wont have any. The place I stayed in had no AC or heat.. and I didnt care.
Sales tax IIRC is 4%, not horrible, given your ER. Flooding is a low concern, I would be curious about HOA fees.
You do however, have to qualify, from the listing :
Buyer must be qualified via Dept. of Agriculture as a "Bonefide Farmer" and be able to show available resources as well as complete a Dept. of Agriculture application.
So, are you going to do coffee, nuts, pineapple or ... all ? Roadside vendor for the tourist visiting Kilauea ?