Donald Trump signed a book for Rudy Giuliani in 2000, writing, 'I promise never to run against you.' It just sold for $54,143 in an online auction.

• An inscribed copy of one of former President Donald Trump's books sold at auction for $54,143.
• A first edition of "The America We Deserve" sold to an undisclosed buyer, The Hill reported.

A copy of one of former President Donald Trump's books, which included a note written in 2000 for then-Mayor Rudy Giuliani, sold last week for more than $54,143.

An undisclosed buyer on Wednesday bought a copy of "The America We Deserve" in an online auction, The Hill and People reported. It was unclear who sold the book.

The RR Auction website has a picture of the inscription, which read: "Jan 2000 - To Rudy - The best mayor N.Y.C. has ever had! I promise never to run against you - Donald."

The auction site had expected the first edition to go for more than $8,000. It described the book as in "very fine condition."

"A remarkable New York City association, long pre-dating their controversial White House years," the description read.

The book, written with Dave Shifflet, was Trump's fourth. When it was published, news outlets reported that he was mulling a run for the White House. A wire report printed in The Dallas Morning News at the time said he was "considering a presidential bid on the Reform Party ticket."

That report also said one of the major hurdles was that Trump didn't like the "barbaric" shaking of hands, which he'd be required to do if he ran. He brought two bottles of "germ-killers" to a Manhattan book signing to make it easier to shake everyone's hands, the report said.

Reviews of the book were mixed. The Rocky Mountain News said: "It's readable enough." The Fort Worth Star-Telegram said Trump "musters great passion" in his arguments, but, "unfortunately, these moments of lucidity get lost in the braggadocio that has kept Trump in the boardroom, and, so far, out of the White House."