OP check out tenso I have seen them mentioned as a good proxy for amazon.jp
I definitely also agree there. I even recall rakuten.co.jp also recommending (I believe) tenso.com as forwarder. There is also a pretty good guide into buying stuff from say for instance from amazon.co.jp on reddit and getting it shipped internationally: http://en.reddit.com/r/MechanicalKeyboards/comments/18387i/guide_bought_my_hhkb_pro_2_from_amazoncojp/
This new knowledge you posted is very bad for my wallet. I can only imagine what kind of goodies I might find on amazon.co.jp like this wrist rest. At least before I was restricted to what I could find in english. Then again the reddit post says the guy saved a little bit by buying direct.
The idea of being wallet hacked always remains true haha. Even to me I find it a little hard to restrain my wallet, everytime I look at something that I really like I stare at my poor wallet whom is probably thinking,"No, not this again!".
Saving a bit is sometimes better than not saving at all imo. Also the thought of buying stuff directly without any sort of stupid restrictions the sellers may impose really allows one to enjoy it all. This is probably also why proxies/forwarders enjoy the benefits of having more international sellers to fulfil whatever they need from places where they simply won't post it internationally. Just as Japan has forwarders so does U.S. I've seen a fair few ebay listings where the seller wants to keep the item within U.S. though really they're just limiting their horizons like every other sellers who ships within the same country. I'm sure virtually every other countries have proxies/forwarders elsewhere, they are all a matter of just finding it out.