Accortding to my research
you cant sell nicotine products in Australia however you can use them and buy them online.
customs lets them through as long as its for personal use and not retail sale.
200ml limit eliquid in australia per package is the official max size cosidered as personal use.
I got this information after a cosiderable amount of emails to australaian customs.
Im not sure about other countrys.
hope this helps