Murphy said that topic-related collections generally start out with little value, but the hope is that, over time, at least a few of the stamps will develop worth.
Of course, while the Moshers profited from that single stamp, their $200 return pales in comparison to some rare stamps.
In May, H.R. Harmer will auction off a stamp expected to go for about $250,000, Bergstrom said. It last sold in a 2003 private auction for $90,000.
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The stamp is an Inverted Jenny, which is probably the best-known U.S. stamp. Issued in 1918, the 24-cent stamp features an image of a biplane upside down—a printing error that resulted in 100 flawed stamps. The one getting auctioned off is in a gold locket, which was given by Colonel E.H.R. "Ned" Green to his wife, Mabel, in 1918.
Bill Gross, well known on Wall Street as the co-founder of bond firm Pacific Investment Management, is also a stamp collector. Included in his collection are four Inverted Jennys that are on loan to the Smithsonian Institution in Washington, D.C., to which he gave $10 million to help establish the William H. Gross Stamp Gallery.