Even if you win an item for a miniscule amount, the total could cost, especially for USA buyers, could be many many times the orig winning bid.
Here are the challenges you are going to face:
1. The desciptions are a bit hard to understand. Sure you could use a translation type service but it's still not a flawless translation. There are descriptive terms that just don't translate, and there are terms we use that they don't, and there are terms they use but we don't. So it should be understood that you are relying on pictures only and the operating condition is generally a big unknown but in most cases, the item will probably require a lot of work, especially the cheaper ones.
2. The pictures are all small. They simply aren't large enough to see any kind of detail.
3. You need to establish an account with a proxy service.
4. You will be charged a fee to fund your account with PayPal. So a $100 paypal transfer to your account is already devalued by the time it's ready to be used.
5. I found that PayPal monetary exchange rates seem to give you less bang/buck than the rates posted by most online exchange rates you'll find. Whatever their internal rates are, that's what you are going to get.
6. When you win an item, it is only the beginning of the process. The winning amount is going to result in more fees:
...6a: You may be charged a winning auction fee.
...6b: You will be charged shipping for the seller to ship the item to the proxy to be held to forward off to you.
7. Because Japan parcel service handles parcels far more delicately than our USA affiliates here do, they generally pack very light. Usually, you will get the item stuffed into a carton barely larger than the item itself. Any voids (very small, almost like the boombox gets a cardboard skin) will be filled with newspaper. If you are wondering how much cushioning effect the newspaper will retain after being stacked on 2-months journey, let me enlighten you.... not much. The proxy will remail the item to you based on your preferences and they may rebox the item to make them internationally shippable. EMS is the fastest but one of the most expensive. They allow larger cartons than surface shipping. It's not easy to plunk down $250 for EMS when you won the boombox (before the fee's noted above) for $5, or $10, or whatever.
8. So your proxy will remail the item to you based on your shipping preferences. They will hold your items if you want to collect/win more items so they can be shipped together to save shipping costs. If you are buying brochures, cassette tapes, trinkets, etc -- no problem. If you are buying boomboxes, especially larger grails, how many do you think are going to fit into one box? Answer is unless you are buying mini's, not many. Mostly, they will be shipped separately.
9. Prepare for your item to be damaged. Over the years, a friend of mine helped me purchase many items. Most but not all of them have had physical damage of some amount. Some where chips/cracks. Some were totally shattered items. Oh, and in case you are wondering, there will be no PayPal/eBay claims to be filed. You are SOL if you find your item damaged.
10. Like some members have shared -- if you have someone who can personally help you effect the transaction, you are well above the curve. If you are a retail customer doing the proxy thing... read this whole thing again.
Recap:
You will pay/lose:
Inferior exchange rates, a fee to change PayPal funds to Japan bank funds, a fee when you win an auction, a shipping fee from seller to the proxy service, a fee to have the item forwarded/shipped to you. So yes, it's possible that a $5 boombox could cost you $150-$200 by the time it shows up at your door.