One of the most famous is the 1975 Roosevelt Dime proof, worth nearly half a million dollars. As far as finding a rare coin like the 2000-P Sacagawea somewhere in the world, DeLorey encourages ...

Errors increase the value of collectibles because a limited ... called planchets, intended for the Sacagawea dollar. As the U.S. Coins Guide noted, the Georgia and other state quarters were ...