If your from Europe, you can order Ivermectine from this shop:
and search for eqimectin 800.
During the payment process, select pick up by postal service and let the prescription be done by the shop.
It works, I have 6 tubes now, maybe you could also order international, but there's customs coming into play.
Edit: fixed the link.
Sorry, link is broken. Use this
https://www.homeovet.eu
and search for eqimectin 800.
My link works. :)
In edit, you have to select the URL, copy it, click the chain-link icon, paste the URL, click OK.