If you need to keep medications refridgerated they'll give you one for $0...but if you need to keep things like soda, water, wine, and beer cold....isn't it worth the$100 just not to have to worry? How much have you spent on this vacation? Is another $100 dollars really worth worrying about? Just rent it, you don't have any worrys about things going bad, sour, and you can go out for the day at the parks without thinking about what you're "coming home to".