What Power / Speed carts actually cost on Mercari Japan right now (21 September 2026) - loose vs boxed vs the antenna bu

[DenjuuImportKai]

Hi all, new here (Crypto on Power, like most of us). I have been buying my Telefang stuff from the Japanese domestic sites for a while and since the Auctions board is mostly eBay/Yahoo Auction sightings, I thought a snapshot of Mercari Japan prices might be useful, because the gap between a loose cart and the antenna bundle is bigger than it looks from eBay.

Five listings live on Mercari Japan as of 21 September 2026, all in stock when I posted this, prices as listed by the seller (dollar figures are at the current rate, before shipping):

• Power Version, cartridge only, seller says tested on real hardware, contacts cleaned, no extras, save battery still holding - ¥800 (about $5.52)
• Speed Version, cartridge only, used with light scuffs on the shell - ¥800 (about $5.52)
• Power Version with outer box and manual, but the Power Antenna is missing (seller states パワーアンテナ欠品 in the title) - ¥4,800 (about $33.12)
• Speed Version パワーアンテナ同梱版 (the antenna bundle), used, complete per the photos - ¥4,900 (about $33.81)
• Speed Version antenna bundle, new and never opened (絶版・新品・未開封) - ¥20,000 (about $138.00)

So a sealed antenna bundle is more than ten times a loose cart, and "box and manual but no antenna" sits closer to the loose price than to the bundle - the antenna is what the price is really tracking. Two things I check every time before buying: the listing photo of the cart back (sellers often write ゲームボーイカラー共通 in the title but only the label photo tells you which version you are getting when the title is vague), and whether the seller says 動作確認済み (tested) versus 起動確認 (only checked that it boots) - the latter is often paired with 電池切れ, a dead save battery, which is a cheap fix but worth knowing.

Region-wise nothing to worry about: Game Boy / GBC / GBA hardware is not region locked, Nintendo's own support page says the GBA is "independent of TV regions", so a Japanese Power cart runs on a US Game Boy Color, and the English patch works the same way on real hardware via a flash cart if you prefer not to play in Japanese.

The catch is that Mercari Japan, Yahoo! Auctions and Suruga-ya do not ship outside Japan, so it goes through a forwarding/proxy service; I wrote up the mechanics (region locks, what the proxy fee and EMS/DHL cost for a cart-sized parcel, why a boxed set in a roomy carton can cost more to ship than a heavier tightly packed one) in this guide: buying Game Boy games from Japan. If you want to see the current Telefang listings in one place, this is the Mercari search for 携帯電獣テレファング I use - a cart is under 50 g so it always lands in the lowest weight band.

Has anyone here compared the Japanese antenna bundle prices with what the bootleg Diamond/Jade carts go for lately? The real thing is cheaper than I expected.