"There's no free lunch" essentially means that nothing is really free, that you always end up paying for it somehow. As I understand it, the phrase originated at a time when many bars and clubs offered patrons a "free lunch" while charging very high prices for drinks. Thus the nominally "free" lunch (with drinks) cost the same or even more as lunch and drinks at other places. (I've heard that there was often a minimum number of drinks that had to be purchased to get the "free" lunch.) "There ain't no such thing as a free lunch" was immortalized by science-fiction author Robert A. Heinlein in his award-winning novel "The Moon Is A Harsh Mistress." In the novel, he also uses the phrase's anacronym, TANSTAAFL, which is still used by some old-line sf fans.

From the reference to Milton Friedman and Robert Heinlein - Heinlein used the phrase in one of his science fiction novels in 1966. Economist Friedman also popularized the expression, but did not claim to have invented it. And, according to Robert Caro, quoted in the Random House Historical Dictionary of American Slang, New York Mayor Fiorello LaGuardia used the phrase (in Latin, no less) in 1934. I don't think anyone is likely to come up with a definitive "first use" of this phrase. The institution of a "free lunch" itself dates back to the mid-19th century, when it was common for taverns to offer their paying customers free food (usually a cold buffet) along with their drinks. Since eating the "free" food required first buying a drink, however, it was debatable whether the "lunch" was really "free" in any real sense. I'd be surprised if the common-sense aphorism "there's no such thing as a free lunch" didn't arise within just a few years of the establishment of the "free lunch" practice in 19th century taverns. from the net Another aspect of the No Free Lunch thesis is expounded in Edward Tenner's 1996 book, WHY THINGS BITE BACK: Technology and the Revenge of Unintended Consequences (Knopf). He doesn't address the free lunch idea directly, but points out in many examples that when we get things that "improve our lives," we are likely to get some things as well that we didn't bargain for. His ideas and examples are interesting and relevant. Anyone interested in the free lunch idea and its many ramifications should read the book, or at least the reviews which you can see thanks to Google. Why Things Bite Back: Technology and the Revenge of Unintended Consequences (Vintage) (Paperback) $9.95. http://www.amazon.com/gp/product/0679747567/qid=1147271684/sr=1-3/ref=sr_1_3/104-0740608-7920723?s=books&v=glance&n=283155