We just returned from a great trip to Costa Rica. We rented a car from Hertz (San Jose Airport) and booked it from the US before we went. When we arrived, they said it was the law that we had to pay an additional $18 day in insurance plus $13-$18 (depending on the deductible you choose) a day for another kind of insurance. We had the car for 10 days so this would increase the quoted price by $310. We said we had car rental insurance through our credit card and they said no matter what we had to pay the $18 but if we declined to buy the additional $13 and go through our credit card's insurance then they would charge $7,000 as a deposit. We did that and our credit card company put a hold on the card and we couldn't use it for most of the trip. We met other people who all had this problem with the insurance (sometimes doubling the quoted price), but none had to put a depo of $7,000. It's a big scam there so just beware that the quote you get is not what you're going to pay. I would suggest booking directly through the Costa Rican websites (not through the US reservation system) and ask specifically for a quote with all insurance included.