I think Mailboxes etc would probably still be able to help you out as they work internationally with FedEx and UPS. And I think it’s worth contacting the place in Playa Herradura to see if they might be able to help.
You could always have the item shipped regular mail to the Costa Rican post office in Jaco. But that might be a lengthy process.
Keep in mind that many airlines also ship cargo, including AirCanada.
One last thing… you might try contacting FedEx and UPS directly and explaining your situation. Perhaps they have a drop off location in Jaco or can arrange something for you.