To many unknowns for me to quote.
Are you cutting in a GFI in the island too?
Anyways it sounds way too low.
I would say more then $500.

After buying matreials, fuel in the truck, and a bit more OH there would be nothing left for the worker. My guess is it would take at least a half day.

"The lady is real nice to me and she is spreading the word about my work already so It's not so bad I guess."

Be carefull with this atitude. What kind of word is she spreading about you? That you are way low in price. Or that you give in on your first quote to a lesser amount by complaining about the price. The idea of giving work away at below cost as advertising may not get you the customers you want.

I remember an auto shop that would give away oil changes at material cost to get more customers because they were slow. This would bring in a lot of the customers that were very cheap with their money and not great for the business. One day the owner got rid of the free coffee pots and found a used pay coffee machine. He said he could not afford to keep buying all the free coffee. So I said "you opened an auto shop to give away repair work but sell coffee?"

Tom