1851 Benjamin Franklin is one of the oldest U.S. stamps. It is designed in blue color and features an imperforate frame. Today, only two mint samples and 100 used Benjamin Franklin stamps are believed to exist. Once denominated in one cent, the design now costs $5,000 to $12,000 apiece, with a huge price of $120,000 offered for used first-day cover examples. 1c Benjamin Franklin stamp fetched $375,000 at Robert.a.Siegel auction that took place in October, 2007.