Boxes began arriving in early November at the Phoenix headquarters of Turning Point USA, a conservative student group with ties to the Trump family.

They contained copies of the new book by Donald Trump Jr., “Triggered,” according to a person who works in the building. The stockpile grew to roughly 2,000 copies, stored in an underused second-floor office under a poster bearing a slogan: “Capitalism Not Cronyism.”

Turning Point is not the only conservative group making bulk purchases to aid Mr. Trump’s new career as an author. At least nine Republican organizations, G.O.P. candidates or advocacy groups are selling “Triggered” or promoting Mr. Trump’s book tour, according to emails obtained by The New York Times, interviews and disclosures filed with the Federal Election Commission.

The president’s son has emerged over the past few years as a political star in his own right, often said to be considering a run for office. It is neither illegal nor uncommon for candidates and political organizations to use books in fund-raising drives: The National Republican Campaign Committee, for example, has also sold its donors titles by the former speakers Newt Gingrich and Paul Ryan.