People often go on shopping sprees to cheer themselves up and a psychological experiment has confirmed that people who are sad, do, in fact, spend more. In the experiment participants viewed either a sad video clip or one devoid of human emotion. Afterwards they could buy an ordinary commodity, such as a water bottle at various prices. Those participants who had watched the sad clip offered almost three times as much money to buy things as the other group. Among those people who were in the 'sad' group those who were highly self-focused paid more than those low in self-focus.
You can read more about this research at