The 66-year-old is close to securing a publishing agreement in the US, with a chapter-by-chapter synopsis already prepared covering potential subjects including Mountbatten-Windsor, Jeffrey Epstein, King Charles, Prince Harry and Meghan Markle, The Sun reported.
The proposed book would be Ferguson's latest attempt to tell her own story after publishing My Story in 1996 and Finding Sarah: A Duchess's Journey to Find Herself in 2011.
"Sarah wants to set the record straight about everything and earn some money to resolve her financial issues," a source told The Sun newspaper.
"There has been a secret bidding war and a deal is close to being secured.
"The notes are compelling and the bidders are excited."
People close to Ferguson acknowledged to The Sun that she had received "a number of deals", although they said direct negotiations had not yet taken place and disputed suggestions she wanted to produce a "tell all" account of recent royal scandals.
Any new memoir would arrive during another turbulent period for the British royal family and follows the publication this week of Swan Song: Diana, My Sister by Charles Spencer, 62.
Spencer's book contains a series of claims about his sister Diana, Princess of Wales, and her relationship with the royal family, including his account of disagreements with the then Prince Charles following her death.
Buckingham Palace has challenged elements of Spencer's recollections, while the King defended his account.
Ferguson has faced renewed attention following the release of documents relating to Epstein.
There is no suggestion former Duchess of York has committed a criminal offence in relation to her friendship with the convicted US sex offender.
Her former husband Andrew, 66, remains the subject of a UK police investigation into alleged misconduct in public office following material released under the US Epstein Files Transparency Act.
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