Specifically, the character of Lord Darlington said it about his companions in Wilde's play "Lady Windermere's Fan". Few people ever quote the rejoinder...
LORD DARLINGTON. What cynics you fellows are!
CECIL GRAHAM. What is a cynic?
LORD DARLINGTON. A man who knows the price of everything and the value of nothing.
CECIL GRAHAM. And a sentimentalist, my dear Darlington, is a man who sees an absurd value in everything, and doesn't know the market price of any single thing.