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 / Updated  / Source: NBC News

The Apple Watch is already out of stock for people buying it the normal way —but there are plenty for sale on eBay.

As of mid-morning Friday there were already hundreds of listings for "Apple Watch" on the auction site, with some selling briskly.

In order to guarantee the validity of their products, some sellers have gone as far as to put their Apple receipts and pre-order forms online. One ambitious seller bought a watch for $399 and is selling it for $800. Another seller already got $560 for a 42 mm Apple Watch Sport, the same device that Apple sells for $399.

If ordered on Apple's website, buyers might have to wait until July before the watches ship.

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--- Nana Sidibe, CNBC