If you haven't booked already, you might want to check the rates listed on http://www.carrentalexpress.com/ vs. island's website. When I booked for this past July, the rate listed for Island on car rental express was considerably cheaper. I then called Island directly and mention the rate I found on the car rental express website and they gave me the car at that price. Not sure about the rates for that time of year, but you might be able to save some money.

I have also booked through car rental express and everything went fine, but prefer to book directly with Island just to eliminate another business being involved. One less step in the process for anything to get messed up in my opinion.