Hi Linda,
You have a lot of options for transportation. The cheapest would be to take the bus. Tickets to Tamarindo are about $8 per person one way. The company is called Empresa Alfaro. Their terminal is in downtown San Jose, about 20-30 minutes from the airport. Taxi will be around $20 for the trip, more or less depending on traffic, from the airport to the bus station. Alfaro has a couple of buses going to Tamarindo each day. You can find a schedule here: http://thebusschedule.com/cr/ (the website is down right now but should be up again well before your trip). Be sure to call the bus station to get an updated timetable as that website is not always updated in a timely manner. The phone number is on the site.
You can also arrange for a private shuttle through Grayline (http://www.graylinecostarica.com/) or Interbus (http://www.interbusonline.com). The cost would be around $50 per person one way to Tamarindo. Call to make a reservation and they can arrange to pick you up directly from the airport or at your hotel the next day if you’re arriving in San Jose late.
.
