An Post also charge a 'handling fee' if your item gets stopped for duty by Customs:
"A fee of 1% of the value, with a minimum charge of €10 per packet or parcel, is charged by An Post for customs clearance of parcels imported from countries outside the EU. This fee is in addition to any duty or VAT payable."
The thing that really annoys me is that Customs will base the duty they charge you on the price of the item plus postage costs, which I don't think is fair.
"If your goods have:
a customs value (including cost, transport, insurance and handling charges) of €22 or less you will not have to pay Customs Duty or VAT
a customs value of more than €22 you will have to pay VAT
an intrinsic value (the value of the goods alone excluding transport, insurance and handling charges) of more than €150 you will have to pay Customs Duty."