Renea, I have heard the Mountainview area is prone to flooding.
Something to keep in mind when you look at price tags, is that while SOME areas might be called over-inflated for what they are, in general, you get what you pay for. All areas are not alike and the current market price reflects the desirability to buyers.
When you get down to the cheapest tier of land and home, that means to me that it is undesirable on a lot of levels other than price, and low price is the main reason it sells at all. Fern Acres is not the worst, but neither does it make it into the top subdivisions list.
It may be tempting to think "oh, the other land is more money because it appeals to people with a more status-conscious materialistic lifestyle." I think it would be a mistake to assume that. A huge reason for increased price in Puna land would be quite simply a more stable organized neighborhood, where there is less chance of rape, murder, robbery and other heinous crimes, where people are working together to shape the community and make it safe to live and with less feeling of isolation.
To put it very bluntly, there are some BAD people in Puna who look at newbies from the mainland as "pickings." Live in the middle of isolation and you are vulnerable. You will need to feel paranoid.
I'm saying this because you don't seem to be quite paranoid enough yet ... you are thinking of price and weather. You have children, so think of safety above all, and also think of proximity to services for your family.
If you do a Google Search of "Fern Acres" + Hawaii + crime you will get some hits for topics on other boards where the topic has come up.
here is an article about recent vandalism to the Fern Acres Community Association board ... which is not a horrible crime, but it speaks to me that there's enough antisocial behavior around to take delight in messing with attempts to get the community together, which I find disturbing.
http://www.honoluluadvertiser.com/apps/p...1/80924089
Knowing that you have children, I even more think you should see how they thrive here before buying property that will be VERY difficult to sell for what you put into it, any time in the near future.