A 90-day tourist visa is available for free upon arrival in Costa Rica for citizens of all countries. Click here for more information on entry requirements. If you're willing to stay longer in the country, you will need to leave Costa Rica and re-enter to get a new 3-month stamp. That being said, 2 weeks in Costa Rica is a good amount of time, unless you really fall in love with the country (which I guarantee you will) and want to extend beyond 90 days.