Well, if you are talking about investing a new computer versus increasing longevity for a year, if you spend 2000 USD in a computer now, or put that same 2000 USD into a mutual fund making a very conservative 7% a year, by spending 100 USD on a battery and buy the computer in a year, you make about 36 USD including capital gain tax. :P Now, while that isn't too much money, the point is, you not only not lose money, you'll beat inflation.
