Question : Is the price you found a good deal?
Answer : Ranging anywhere from $651 to $2,346, prices for BIO to SJO do change a lot more than most routes from Spain and Canary Islands. However, the sooner you book, the more you'll be able to save.
Question : How long do most people visit San Jose?
Answer : Of course you're not most people, but if you were, you'd stay roughly 10 days.
Question : Would you be willing to change your travel days if it saved you money?
Answer : The lowest-cost day to fly in March is Thursday. Flexibility is paramount when booking travel plans in order to keep travel costs down.