Taxes are the biggest problem when I order in the US( or somewhere else outside Europe)
And the larger the order, the more likely you'll be caught for customs and VAT. Sometimes a priority enveloppe will slip trough, then you are a happy camper!
The other problems are sales. Because when I buy something on sale, our customservice will handle it if it was the original price. So then you have to pay even more taxes!
Only when there is a sale at onlines shops at the UK I will order there, UK is Europe and so taxfree for me!