"Below an income of $60k per year, Americans are unhappy, and they get progressively unhappier the poorer they get. Above that, we get an absolutely flat line in terms of happiness. Money does not buy you experiential happiness, but lack of money certainly buys you misery." - Daniel Kahneman

http://www.ted.com/talks/daniel_kahneman_the_riddle_of_experience_vs_memory.html