Volume, volume, volume.
The economy of scale in the US is why it is cheaper there. You'll find this pretty much across the board in brand-name electronics. I know there are some who "know of this place or that place" where they can get a deal on the "X-J-Red 27" camera or such and such lens, but generally speaking, you'll find prices cheaper in the US for many of these brand name electronic goods.
But there is another factor at play... (coming to you from a guy who just bought a camcorder in the US last month).
As you may know, HD-TV is going all out in the US, and by 2009 you won't even be able to buy a 4x3 analog TV anymore. HD Camcorders came out last year, and they are now on ver.2 in the market. I got an HDTV camcorder for about $1200 US (Best Buy) and the advent of this new tech is already having a ripple effect on digital camcorders and their older analog cousins. The picture quality is wicked and I figured some of the things I'm shooting are videos I'll want to keep for decades to come.