Hey mate, calm your farm. You've asked a really odd question and given two days to get the response you wanted. Do you even know what propolis is and how a beekeeper might collect a half a litre? Import it by all means, just declare it to customs for checking, treatment or disposal.
Maybe, if you're into traditional methods why not team up with a beekeeper and go have a look at how a hive works, and collect all the propolis from it? Methinks you might need to make a few trips.......