Art lovers could pick up a bargain when Charles Saatchi sells off part of his multimillion-pound art collection at auction without putting any reserve prices on the work.

Fifty lots, including a four-poster bed by Tracey Emin, will be sold at Christie's Thinking Big sale in central London in October.

Normally they would have a reserve price - a minimum level bidding has to reach before they are sold - and the decision not to have one means work could in theory sell for as little as one pence.

In reality, artist's dealers will probably bid for work if it looks like they might sell for prices so low they would damage their reputation.

Many of the lots, including work by the Chapman Brothers and Conrad Shawcross, are so big they can not be exhibited at Christie's but will instead go on show in a huge former Post Office depot in central London.

Saatchi and TV chef Nigella Lawson were granted a decree nisi - the first legal step to ending their 10-year marriage - at the High Court earlier this week.

Saatchi, 70, and Lawson, 53, now have to wait for a decree absolute, which is usually issued six weeks and a day later, ending their marriage.

Philippa Adams, senior director of the Saatchi Gallery, told the Guardian the sale has "absolutely nothing to do with the divorce".

She said: "We have been working on this for a long time. I can categorically state that."

Pictures published last month showed Saatchi holding his wife by the throat as they had an argument on the terrace of a restaurant.

He dismissed the incident as nothing more than "a playful tiff" but then accepted a police caution for assault.

Christie's head of post-war and contemporary art, europe, Francis Outred, said the sale had been planned for around a year.

He said: "The artists come from five different continents and the exhibition and auction will be a fundamental celebration of the sculpture in the 21st century. Thinking Big refers to the huge ambition and imagination of the artists here, as much as it does to the scale of their work, and to the power of educating young people about art."

All the proceeds from the auction will be used to keep the Saatchi gallery open to school visits for free.