Shipping to the U.S. is one thing. Trying to send a bum unit back over the pond is a different story. I once purchased a Joby gorillapod on ebay from China, with free shipping. Got the item and it was a fake. Although I could return it, the shipping costs were more than what I paid.
It's a convenience to be able to order from Amazon.uk, but it's a different monster and there's no way you're going to be able to demand the same level of customer service as Amazon.us. I hope you can find a cost effective way to deal with this. Also consider whether you can get a refund instead of a repair or replacement because shipping will ALWAYS be unmanageable. The warranty might be another obstacle with an overseas purchase.
I almost got tempted by the good exchange rate on this the other day then luckily it seeped into my brain that this wasn't a short throw projector. I would have really been stuck had I pulled the trigger.