Hi Lisa,
Thank you for your enthusiasm in trying to help prevent the spread of the Zika virus here in Costa Rica. We aren’t sure where you can buy large quantities of insect repellent for re-distribution but there are some big box stores in the San Jose area like Walmart that would probably stock a good amount. If you haven’t already you might also want to reach out to the Ministerio de Salud (health ministry) to coordinate efforts in the priority areas. Here is a recent article in about their effort in the La Nacion Newspaper: Curso lectivo empezará con campaña de guerra contra el zika. Best of luck with your project and thank you again.