They actually have to check you though.... and doesnt it have to be over £250 pounds before you have to pay tax?
Last year when i was in japan i bought a digi cam (all cameras have english menu too)
I went to softmap i think which is pretty cheap. It had just come out I checked on the internet a couple of weeks later and the bloody thing was the same price from someone store back in the UK the buggers.
I would do as much searching around before you go... ask in some american computer forums.