Local airlines Nature Air and Sansa offer daily flights to/from Tamarindo, both from San Jose and Liberia. These flights are especially helpful when traveling to San Jose.
Shared shuttles are a great option, offering fixed schedules, set pickup/drop-off points, and a more comfortable ride than the public bus. InterBus is a well known service that offers an air conditioned van with comfortable seats. The will drop you off at the nearest hotel to your destination.
Average Cost: $55 – 65 per person (San Jose to Tamarindo, 5.5 hours), and $50 (Liberia to Tamarindo, 1.5 hours)