Seriously, here's how to buy happiness:
In brief, research suggests that once you have enough income to live a comfortable and satisfying life, you'll derive more happiness spending money on others than spending it on yourself. (See e.g. research by Faust, as recounted by Goethe.) Also, money spent on oneself is better expended on maximizing experiences (by traveling, for example) rather than piling up things.
(Update on the disappearing video problem: At least until the bug has been fixed, I'll be including an explicit link in addition to embedding the clip in the post.)