I had gotten a recommendation a few momths back from Dani to try Noppin, the proxy service that she uses to order merchandise from Japan. I've tried them a couple of times now and I think it is possible to save money using them rather than JAUCE and kuboTEN to buy stuff from Yahoo! Japan Auctions but it's not entirely clear to me how much.
There are a couple things I like about Noppin right off the bat. Like JAUCE they offer "live bidding" - when I submit a bid request on an auction through them, they go ahead and make the bid. With kuboTEN you have to wait up to 12 hours or so for your bid to actually go up (or at least that was the case the last time I used kuboTEN which was probably last winter). I also like the fact that they use a multiplier on the deposit for the bid limit - so if you deposit 2000 yen your bid limit is 6000 yen. Other services use the actual amount of your deposit as your bid limit. One drawback is it isn't as easy as it is with kuboTEN and JAUCE to apply you deposit to your payment - I'm pretty much just leaving the 2000 yen I have on deposit with Noppin there for future use.
The only things I haven't liked so far is that they aren't real good at sending out emails when they've received your items - I usually have to log in to see if they've gotten my stuff. I was also kind of annoyed when they basically shut down in mid-August for a long weekend for Marine Day - including turning off live bidding. It coincided with the release of BBM's 2nd Version set and I had to use JAUCE instead (I could have waited but I like to get the new stuff as soon as it comes out).
Noppin's auction fees are calculated a bit differently than the other outfits. They have a set fee (500 yen) for auctions that end at 4000 yen or less. For auctions that end between 4000 yen and 40000 yen, the fee is 12.5%. Auctions that end for more than 40000 yen have a fee of 5000 (12.5% of 40000) plus 7.5% on the amount over 40000 yen. Note that the auction fee is only calculated using the ending value of the auction - domestic shipping (from the seller to Noppin) is not used in the calculation.
In addition to the auction fee, Noppin also charges a 250 yen "bank wire fee" per payment to a seller - so if you won multiple items from a single seller but Noppin only has to send money once to the seller, you only pay this once.
Noppin also charges 3.5% "payment handling" when you make a payment to them.
This is a lot of numbers to throw at you so let me give you an example. The first item I bought through Noppin was this year's 1st Version set back in April. The auction ended with a price of 4800 yen. Domestic shipping from the seller to Noppin's office in Fukuoka was 510 yen. Noppin's auction fee was 600 yen and the "bank wire fee" was 250 yen. The "payment handling" fee worked out to about 215 yen. So the total cost was 6375 yen.
Doing the math on the other proxy companies I've used (or at least still use :-)), JAUCE would have had an auction fee of 1184 yen (800 yen plus 8% of 4800), a "bank wire" fee of 300 yen and a "payment handling" fee of 322 for a total of 7116*. kuboTEN would have had an auction fee of 1531 yen (1000 yen plus 10% of the auction price plus shipping total of 5310 yen) and a "payment handling" fee of 266 yen for a total of 7107 yen. So in this case Noppin gave a savings of over 700 yen. But our stuff is still in Japan - we haven't talked about shipping to the US yet.
*I need to point out that these are the fees that were being charged back in April when I first did these comparisons. Since then JAUCE has dropped their fees to 400 yen plus 8% so the auction fee would have been 784 and the "payment handling" fee would have been 205 for a total of 6699 which is still 300 yen more than what Noppin's fees were.
Last year I used kuboTEN to pick up the 1st Version set. EMS shipping for it and the Tigers 80th Anniversary set was about 1300 yen. So imagine my surprise when Noppin charged me 2800 yen for EMS shipping for this year's set! That ate up any savings over the other two companies. In fairness to Noppin, however, their shipping costs appear to be in line with what JAUCE charges as well - I just paid 3140 yen to have JAUCE ship the 2nd Version set to me. I haven't done an EMS shipping request through kuboTEN since last winter so I don't know if their prices have gone up as well.
To sum up, I think Noppin is a good outfit to use that may save you a bit of money over JAUCE and kuboTEN (both of whom I would still recommend as well) but be ready to pony up for shipping to the US.