A few months ago I had a very irate buyer in the UK who threatened to leave feedback to "warn" other buyers because he had to pay duties upon receipt. I sent him the Ebay text regarding the buyers responsibilty and luckily that was the last of it.

However after dodging this possible red dot I now put a notice at the bottom of every one of my listings - straight off the Ebay website as has been mentioned above. On top of which, if an item sells to the UK, I tell the buyer upfront that they are probably going to get dinged with duties, so, with their permission I separate their items into two or more packages, declare the full value on each package and just make sure that it each pack comes in below GBP18.00. In terms of postage, what I charge usually covers being able to split the packs up with no extra to pay. Buyer is happy and I get sales and there are no negative repercussions.

Also, if the buyer leaves negative feedback which relates to duties/fees etc, I'm pretty sure it's one of those times that Eaby will remove it. I'm sure there is info on the site somewhere about acceptable feedback.