Hello alwalt, please visit this link specifically:

http://eventidestore.com/powersupplies1.html

You will see a drop-down box with the four power supply options.  Simply select the power supply you want and click "Add to Cart."  The US (p/n 105278) adapter is probably what you need.  There are no exclusions prohibiting you to place an order from Costa Rica, so you should be good to go.