A “buckraker” (buck + muckraker) originally referred to a muckraking journalist who raked in bucks through speaking engagements, books and other sources. “Buckraker” also refers to a politician who sells principles for the big bucks of books, television, etc. A “buckraker” today refers less to a corruption-exposing “muckraker” than to someone who “rakes bucks.”
 
   
The Free Dictionary
buck·rak·ing (bkrkng)
n.
The practice of accepting large sums of money for speaking to business or special interest groups, especially when viewed as compromising the objectivity of journalists.
[Blend of buck and muckraking, gerund of muckrake.]
buckraker n.
 
Word Spy
buckraker
(BUK.ray.kur) n. A journalist who uses their connections and knowledge to earn a significant amount of money outside of their regular job. —buckraking, n.
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First Use:
Any history of Washington journalism would surely mark June 1972 as the beginning of a new chapter. That was when Bob Woodward and Carl Bernstein started investigating a peculiar burglary at Democratic National Committee headquarters in the Watergate. Thus began the era of the Washington muckraker. Woodward and Bernstein became famous, journalism became glamorous, and “investigative units” proliferated at newspapers and television stations across the country.
 
The same history might mark February 1985 as the start of the next era. That was when Patrick J. Buchanan went to work at the White House and his financial disclosure statement revealed, to widespread astonishment and envy, that he had made $ 400,000 as a journalist in 1984. This included $ 60,000 for his syndicated column, $ 25,000 for his weekly appearance on “The McLaughlin Group,” $ 94,000 for Cable News Network’s “Crossfire,” $ 81,000 for a radio show, and more than $ 135,000 for 37 speeches. Welcome to the era of the buckraker.
—Jacob Weisberg, “The buckrakers: Washington journalism enters a new era,” The New Republic, January 27, 1986
 
Notes:
When searching for the earliest use of this blend of buck (slang for a dollar; 1856) and muckraker (someone who exposes wrongdoing by prominent people; 1906), I found a number of citations from early January, 1986. However, they were all commenting on a piece by Jacob Weisberg that was to appear in the January 27 issue of The New Republic, so I’m crediting that article with the first use.
 
Wikipedia: Jacob Weisberg
Jacob Weisberg (born 1964) is an American political journalist, serving as editor-in-chief of Slate Group, a division of The Washington Post Company, and a columnist for the Financial Times. He served as the editor of Slate magazine for six years, until stepping down in June 2008. He is the son of Lois Weisberg, a Chicago social activist and connector celebrated in Malcolm Gladwell’s book The Tipping Point. Weisberg’s father, Bernard Weisberg, was a prominent Chicago lawyer and, later, judge. His parents were introduced at a cocktail party by novelist Ralph Ellison.
 
Weisberg is a frequent commentator on National Public Radio and also writes a weekly column for the Financial Times. He previously worked for The New Republic in Washington, D.C., was a contributing writer for The New York Times Magazine and a contributing editor to Vanity Fair. Early in his career, he worked for Newsweek in the London and Washington bureaus. Weisberg has also worked as a freelance journalist for numerous publications.
   
Google News Archive
17 May 1987, Rock Hill (SC) Herald, “Free press contradicts itself” by Chuck Stone, pg. 4A, col. 3:
If anything, journalistic credibility has worsened because buckrakers are replacing muckrakers.
   
Google Books
Snollygosters, airheads & wimps:
John Clay’s dictionary of presidential words
By John E. Clay
Red Wing, MN: Lone Oak Press
2000
Pg. 59:
BUCKRAKER (SL) noun - a former high government official, either elected or appointed, who “cashes in” on his government experience and connections with a high paying job as a business consultant or lobbyist.
       
Word Wizard
ken Greenwald
buckrake / buckraker / buckraking
Posted on: Tue Nov 17, 2009 7:21 pm
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After checking through several examples, it does seem to me that the present usage has evolved somewhat to include a wider net then the above definitions, which originally referred mainly to journalists speaking to business groups (see 1986 and 1987 quotes below).
 
Here is my stab at an updated definition:
 
BUCKRAKING verb: A public figure or organization (politician, media figure, . . . government, group . . .) either cashing in on their fame/prominence/celebrity/stature and earning significant sums of money (legally and ethically or unethically; illegally) outside of their regular job/function (or former one – think Bill Clinton, etc.), or to advancing a self-serving private agenda.
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1987 “News Media’s ‘Buckraking’: Moonlighting Proves Lucrative, Controversial [The Moonlighting Journalist’s Road Can Be Paved with Gold] . . . [[journalists]] Evans and Novak had lured 125 consultants and financial analysts (at $350 a head) to hear public officials speak ‘off the record’ at one of their ‘regular forums.’ The chief attraction this time was Treasury Secretary James A. Baker III, who spoke free as a favor to the columnists. . . . ‘Evans and Novak—these guys are in some business other than journalism,’ Harmon [[an excluded journalist]] fumed . . . But it is business. Wednesday’s event earned the columnists about $14,000 each . . .The New Republic magazine coined the term ‘buckraking’ (muckraking for big bucks), and it has caught on . . .”—Washington Post, 18 April, page A1> [[Note: ‘Muckraking for big bucks’ doesn’t fit any definition or usage of ‘buckraking’ that I’ve seen.]]
     
New York (NY) Times
Op-Ed Columnist
The Great Tea Party Rip-Off
By FRANK RICH
Published: January 16, 2010
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Steele is representative of a fascinating but little noted development on the right: the rise of buckrakers who are exploiting the party’s anarchic confusion and divisions to cash in for their own private gain.