I ordered some computer parts.

It turns out that the advertised product was
a brand name drive but it turned out to be a white
label(IE, the manufacturer will not guarentee 
the product, the seller will.)

I did NOT see a mention of this at the time of 
purchase(the seller has rectified that since)

Originally the seller offered a refund for the
price of the item only, not shipping.
I was also responsible for returning the item
on my own bill.

I got a full refund by disputing the credit card
charge.  However, I still paid to return the item.

I have some questions for you and I hope they 
help guide you:

1-Is the dealer's native language different from 
your own? If so, can you communicate with him/her 
in that language?

2-Have you consulted your local post office about 
international mail fraud?
Also, have you considered asking the post office 
about sending the cel to the dealer, postage due?
Namely, the dealer will be stuck paying for the 
postage.  
Are there any Japanese dealers/friends you know 
and trust?
If you do, I would ask them about mail fraud 
reporting in Japan.  

3-I think you are entitled to a $150 refund at 
minimum. Do you still have the part of the 
packaging that shows how much original shipping 
actually was?
Remember how much you were overcharged? If the 
packaging was nice, like some people have bought 
nice plastic cases for me, I can understand the 
cost being greater than postage alone.

4-Can you work something out with your friend to 
get the cel you want?  Maybe trade with him/her?
There's not