Bookshop owners will be joining supermarket queues when the new Harry Potter novel goes on sale at midnight on Friday. The independent shops will be stocking up on copies at Tesco, Asda and even Wilkinson, the hardware store, because their prices are lower than the wholesale rate.

Discounting on Harry Potter and the Deathly Hallows — the seventh and final book in the series — is so heavy that one big retailer is advertising it for sale for as little as £7.99. Asda and Tesco are advertising it at £8.87. The recommended retail price is £17.99 and the wholesale price is £9.89 — which means that most retailers are selling the book at a loss to attract customers.

Matthew Clarke, of the Torbay Bookshop in Paignton — voted independent of the year by The Bookseller magazine — has bought wholesale stock to satisfy his customers on Friday and Saturday but is planning to go to his local Tesco for the rest of his stock because it is cheaper. He is selling the novel at £10.99 and will enter into the spirit of the launch by opening at midnight on Friday with staff dressed as wizards, and a real owl. But he will not be enjoying any profits as his margin is only £1.60 a copy.

He said: “The magic of Harry Potter has gone mad. Nobody is making any money in the distribution of this book. Amazon, Tesco . . . are either breaking even or losing money.” Asked why he bothers to sell it, he said: “Because we are a community bookshop. We do it because we have a lot of fun. But I’m pleased this is the last one.”

Localbookshops.co.uk, which represents 560 independents, said that the majority of its members would also be bulk-buying from the big retailers rather than wholesalers or direct from the publishers.

Chris Conway, its managing director, said: “We might have silly situations where bookshop staff will be crossing over the road with armfuls, but there’s a very serious side to it, too. The wider issue is that there must be something fundamentally wrong with an industry that’s incapable of maximising returns from a runaway success. HP7 would probably have sold in similar numbers at £25 but, instead, it’s marked down as if it were terminal stock. The ongoing effect of such deep discounting is to reduce the perceived value of all books.”

He said that the Harry Potter publisher, Bloomsbury, had “failed to protect the value of the brand”, turning novels into a commodity to be sold cheaply like cans of beans.

Charles Walker, the Conservative MP for Broxbourne, is calling for an Office of Fair Trading inquiry. He said: “This price war takes away the oxygen of economic survival from the smaller businesses, making it difficult to remain viable . . . Unfortunately, the magic of the book is lost on some people, who are just desperate to make a fast buck.”

After Asda accused Bloomsbury of hiking up the recommended retail price, there were reports last night that the publisher had cancelled the supermarket giant’s order for half a million copies of the last book.

J.K. Rowling, the author, has asked bookstores selling the novel in more than 200 countries to display a poster of Madeleine McCann, the girl abducted in Portugal on May 3.

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