Hello!
They run from 10 - 12 dollars, I think. Don't know why but they are not the same price from resort to resort.
We love them - a good value (we have coffee in the morning and sodas at night), plus they make great souveniers!
DH and I will bring ours on the bus in the morning, full of coffee (don't know if you're supposed to bring drinks on, but no one has ever said anything to us) - then I clean them out once we get to a park and toss them in the backpack. If someone needs a drink, we fill them at the water fountains throughout the park (water is not the best tasting - but $2.50 a water???)