There ain't no such thing as a free lunch.
"Gospodin," he said presently, "you used an odd word earlier--odd to me, I mean..."
"Oh, 'tanstaafl.' Means ~There ain't no such thing as a free lunch.' And isn't," I added, pointing to a FREE LUNCH sign across room, "or these drinks would cost half as much. Was reminding her that anything free costs twice as much in long run or turns out worthless."
"An interesting philosophy."
"Not philosophy, fact. One way or other, what you get, you pay for.
. - The Moon is a Harsh Mistress, Robert A Heinlein