In order to rent a cell phone in Costa Rica, you must contact the rental company and have it deliver your appliance at your hotel, because they don’t have an office at the airport. Some agencies that work well are Cell Service and Costa Rica Cellular Connection.
If you are going to rent a vehicle in Costa Rica, you can ask your car rental company about rental cell phones. Some companies offer a phone rental service for their customer’s convenience. However, if you do have a phone with interchangeable SIM/GSM card, that would be your most cost-effective option.