Hey, I just bought a Tenkeyless Archiss from J-Goods and the quote was as follows:
First payment:
AS-KB87T - 7980 JPY
5% fee - 399 JPY
Shopping commision fee - 1649 JPY
----------------------------------
Total - 10,028 JPY
2nd payment:
International postage - (some weird symbol)
Settlement fee - (some weird symbol)
Postal insurance fee - 0 JPY
Ah, I went with
Tenso instead as that was what Rakuten suggested when I tried to checkout (yes, I'm gullible).
From what I see, as long as you provide them with the item name, quantity and shopping cart link, J-Goods will do the translation and purchase for you. Tenso just gives an address and some other shipping information that was not immediately obvious to me, and then expects you to use that to shop by yourself

Still, I appear to have succeeded with the help of translate.google.com. My first payment's breakdown is:
AS-KB87T - 7600 yen
Sales tax - 380 yen
Shipping (approx.) - 490 yen
Total - 8470 yen
Estimating the weight of the package to be just above 1 kg, my second payment might be:
Service fee - 980 yen
Shipping (Asia) - 2100 yen
Total - 3080 yen
That means a net total of 11550 yen.