I recently received some stock mufflers from Dale Avon in Canada, the were sued but only had like 700miles on them. They were logged as a gift, BUT he put $400 value on them, just in case they got lost, cos that's probably how much they are to replace. I had to pay £67 in excise/import/VAT for them. But with an email to customs from Dale, stating that they were only worth app' 70-$100 they are going to re-evaluate the VAT.
It goes like this:
Anything purchased over £18 is subject to duty.
Any GIFT worth over £36 is subject to duty.
Tip: Tick the gift box, but make the value negligible.
I am never purchasing from US vendors due to them not marking as gifts... come on, ya'll could say we are friends on here eh? And keep the transaction private :P