A good stock is an even better buy when it's on sale, even if your primary goal is immediate and reliable income.Need investment income? Dividend stocks are an obvious option to consider. If you're looking for one you can comfortably buy and hold forever, however, the matter becomes a bit more complicated. "Forever" is a long time, after all -- the underlying company needs to be one you're confident can continue performing well into an unforeseeable future. Not every organization is built with this sort of ...