Within the EU you pay the local VAT / taxes and no additional import VAT or duty when sent across the EU
For goods imported from outside of the EU you pay local taxes then any import VAT and/or duty as applicable for the type of goods, any thresholds and whether or not there are any alternative provisions in place. There may or may not be the ability to reclaim local taxes on exported goods
Can't say I'm rich enough to purchase from them but they are how I discovered the G&G SR30. Strange gun to be upgrading as it's only out a few months.