Try AmiAmi or Amazon.co.jp for ones from Japan.
The standard New 3DS didn't even came in the America yet, therefore the cover plates can't be obtained anywhere in the region. However, there are in Europe, Australia and Japan.
The cheapest cover plates are more likely to be found in Europe, since the price (even with conversion rates) is generally cheaper than in Japan and especially Australia. In that case, try your luck at Zavvi and GAME. These may be sold at the MSRP, but they're probably the cheapest ones you could get and they do ship worldwide. And the shipping fees are probably even cheaper than in Japan or even Australia.
Can't manage to place an order in Europe? Try any Japanese online store that has these products and make sure you have your Tenso.com account ready for that. Be prepared to understand some basic Japanese in order to place orders. Or there's also Nippon-Yasan, but some of the cover plates can be a bit more expensive than they should.
thanks!
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What do you mean by standard? I have the new nintendo 3ds xl, thanks for the suggestions!
Well, I meant the smaller New 3DS model that supports interchangeable cover plates. Never heard of the New 3DS XL ones, though.
The New 3DS XL doesn't have interchangeable cover plate. Sorry, you are stuck with what you have.
That was my mistake. I didn't see the xl part, so I thought you imported a small New 3DS. Yeah, the face plates are only for the small size not the LL/XL. You can get skins or decals for them though.
https://www.decalgirl.com
This is a really good site for decals. You can get a matte finish or glossy finish for the same price, too.
Skinnit also offers decals/skins for the 3DS XL. You can make your own too: http://www.skinit.com/device-skins/gaming-skins/nintendo/3ds-xl
I've ordered from them before, and I am in Canada. I made one for my fianc? xbox controller, and five years later it still looks good and it isn't peeling. It takes about 2 weeks to ship it here.