Green’s Dictionary of Slang

(orig. US) money that is earned quickly, and poss. illicitly.

1949		in New Yorker 5 Nov. 82: Tryin’ to hustle me a fast buck.
1951		N. Algren Chicago: City On the Make 67: The swifter type thief approach their work with the same lofty hope of [...] making a fast buck.
1952		I, Mobster 38: It was Prohibition and everybody all over town was making a quick buck peddling alcohol.
1960		J.P. Donleavy Fairy Tales of N.Y. I i: And I’m on the pier pushing a cart where every guy’s after a fast buck.
1971		J.D. Horan Blue Messiah 315: If you are only looking to make a fast buck, I would advise you to forget it.
1989		T. Blacker Fixx 138: A publisher greedy [...] enough to let down an old friend in order to make a quick buck.
1989		M. Amis London Fields 356: Books: one way to make a fast quid.
1993		D. Jarman diary 11 Jan. Smiling in Slow Motion (2000) 291: Culture never had a chance, no one ever had any value other than the quick buck.
1999		Observer 11 July 30: We all want a fast buck.
2000		Guardian Weekend 8 Jan. 12: The quick buck may have been tempting to the [...] Nationwiders.
2011		Sky News 3 Oct. 🌐 Don’t the Brits love making a fast buck?