Don't buy itAll you underpaid and unemployed folks trying to get by in today's bad economy can file this one away in the "Why Didn't I Think of That?" category. Don't worry -- most of us wouldn't believe we could successfully sell loads of fake stock in a non-existent Filipino gold-mining corporation. But according to Securities and Exchange Commission (SEC) officials, Foster City resident Elvira Gamboa, 57, did just that -- and made off with a nice pot of cash.Until now.On Friday, the SEC filed