I have just checked the australian customs homepage for customs and taxes.
It seems, the GST (Goods and Services Tax) will be paid by the vendor at the point of sale and not at the border.
That is for importing goods by post or mail with a value of 1,000 AUD or less (around 555 EURO).
The vendor will normally add this to the price.
When buying with clove for example:
For a full delivery destination list and costs of shipping to each country, please add your required items to the basket, proceed to checkout and select the delivery destination.
Shipping options and relevant pricing will then be provided.
Just for clarification: I haven’t tested it; so it’s just an educated guess.