I'd rent down there. If near Tamarindo, Matos surf shop is pretty legit like $100 for the week and if I remember correctly I believe Delta is one of the most expensive at $200 each way. Matos will even order a new board for you to ride for the week if you give them enough heads up and only charge $150 for the week I believe.
1. Depends where in CR you are going? Have been many places most rent rideable (brand name not soft tops or bics) longboards $20 a day. 2. What is purpose of trip? Is it a surf trip, like three sessions a day first light to last light, or a vacation with family girlfriend. 3. Based on your skills and the fact sounds like a vacation I would strongly advise renting. If you let me know where some places you can see inventory on line and even reserve. 4. Delta will put a gun to your head for fee:http://wavetribecompany.com/2014-airline-surfboard-boardbag-fee-guide-for-surfers/