I've always felt that "Money can't buy happiness" is total BS, probably made up by a woman or an overly-idealistic poor person.
Tell that to Robin Williams and Kurt Cobain or the famous newsreporter who slammed his car into the wall a few weeks ago.
Listen, let me tell you the REAL deal, broskie. Here goes:
If you're only problem in life is financial burdens, then, yes, of course money is going to buy happiness. Furthermore, I agree that having more money may make someone more happy.
However, if you're riddled with a host of other problems, that money cannot fix, then, all of the money in the world will not make you a happy person. It may assuage some of the negative feelings, but you probably wont be as happy as you want to be.
Holding all extraneous variables constant, yes, money can buy happiness. But, in life, its often the extraneous variables that lead to sadness, and some of these things cannot be fixed with money. In the end, its really contextual. So, it really all comes down to many factors. I mean, Robin Williams was diagnosed with an incurable disease, then wound up killing himself. Money couldn't cure his disease.