We will try to answer to this question giving you some tips.
Buyers beware, the rates you see advertised in big print may become so inflated depends of the local taxes, airport surcharges, additional driver fees, insurance, gasoline bills and drop-off charges that you will end up paying more than double what you expected. You need to learn and ask about these extra charges before paying anything.
The advertised rate may be valid only during the off-season or only for a car size that you would find unsuitable. Recently, major booking engines have become more transparent about car rentals and now, usually show the total cost of the rental, including estimated local taxes and fees, early in the booking process.
Car rental company also like the airlines have adopted an electronic management. That means that their computers can quickly readjust prices according to the changes in the supply or cars available, and so the rental rate you quoted is valid only at that moment.
Unless you reserve immediately, the rate is likely to change