There is one domestic airline servicing flights from San Jose (SJO) to Limon (LIM) and back. Sansa airline has a terminal next door to the SJO international airport and is a short walk that takes less then 5 minutes to reach the terminal. When staying at a hotel the night before your shuttle or taxi can drop you off directly at Sansa's terminal.
Note: larger groups may want to consider ground transportation due to weight restrications for baggage.