Chilimike is a vet and taking a cab might be his thing but I disagree strongly. First, any cab that will do the airport to Jaco run for $50 is not going to be a real cab on a meter. On the meter, Jaco would be closer to $150 or $200. That means a pirate taxi with no license and probably no company to answer to.
Pirate cabs can be dangerous, especially at night as they have no one to answer to short of the police. In my opinion, a new guy coming in to the airport at night with all his stuff (money, CCs, passport) and jumping in with a cab driver with no meter, no company and no license is asking for trouble. Do a search on the number of people robbed by taxi drivers in Costa Rica.
Most of the guys at the airport charge $100 which is the same as I charge and there is 0% chance I am going to rip you off. That extra $50 you spend is nothing compared to the problems you will have if a taxi driver decides to dump you off on the side of the highway halfway to Jaco and steals all your stuff leaving you with no passport, no money, no possessions and no phone in the middle of the night in the middle of nowhere in a foreign country.
Edited to add these links to good articles on taxi problems in Costa Rica:
http://www.costaricantimes.com/english- ... port/20876http://www.qcostarica.com/2013/02/10/tw ... -san-jose/http://costarica-information.com/travel ... tion/taxishttp://matadornetwork.com/trips/5-shitt ... osta-rica/