3. Should you invest in “forever” stamps? In 2007 the U.S. Postal Service began selling such stamps, which will suffice for first-class postage at any time in the future, even when rates rise. These stamps cost $0.49 in early 2015. Would it be a good investment to buy a “lifetime supply” of them? To render your judgment, compare the historic increases of postal rates (see www.vaughns-1-pagers.com/economics/postal-rates.htm) with the CPI (page 891). For example, you could convert postal rates at each of the dates of change to the cost in today’s dollars, and then see if there appears to be a recent trend that you can project into the future.