Sony Alpha HVL-F56AM is very cheap in US!

I am asking my wife to buy the Alpha flush device for my Sony Alpha A100.

The candidate is HVL-F56AM and HVL-F42AM.

But please look at the difference of prices! Is there any difference between two?



Today's price in US:

• HVL-F56AM: US$308.88


• HVL-F42AM: US$299.00


• HVL-F36AM: US$146.03


• A100 Body: US$579.88

And I'm surprised at the low prices of HVL-F56AM! Let me introduce the price of it in Japan. It costs \45,720 (05/12/2008), which might be US$457...



Today's price in Nihon:

• HVL-F56AM: \46,720


• HVL-F42AM: \27,767


• HVL-F36AM: SOLD OUT


• A100 Body: \74,250

Even the original price of HVL-F56AM in US, US$369.99, is also cheaper than in Japan. I'd be able to buy it soon if I were in US now...

But why is it cheap in US?