Opportunity Knocks
BBC reports Potter first edition for sale
The sellers of eBay describe the book as a "genuine first print, first issue hardback" and detail distinctive errors on the title page and first page.
The sale price has reached 1,200 so far, with three days of bidding to go.
Publishers Bloomsbury told BBC News Online it was impossible to verify the copy's authenticity without seeing it.
The sellers say they have kept the book unread and sealed in an airtight box since buying it in 2000 for 600.
They have decided to auction it for money to invest in their business after watching its value soar over the past four years.
The sellers' entry reads: "This was a really good investment for us."
They say the book can be proved to be a first state copy because the author's name on the reverse of the title page is printed as Joanne Rowling.
An eBay spokeswoman said potential bidders could examine scanned pages from the book (although please keep in mind, IF she's scanning it, you're going to run into spine damage at Least) on the website or e-mail the sellers for more information.
She advised buyers to study a seller's feedback according to the guidelines provided by eBay.

In January this year, an uncorrected proof copy of the first Harry Potter book - with the author's name spelled wrongly - sold for 1,250 at auction.
And sadly a signed first edition of Harry Potter and the Goblet of Fire was sold by the author's father for 27,500 at auction in 2003.
HERE