There are approximately 15 known 1999 State Quarters struck on Experimental Planchets. All five states in the 1999 series (DE, PA, CT, GA and NJ) have been discovered. These Experimental State Quarters have sold for as high as $10,000 each, depending on which state, the coin's condition and which type of experimental composition was used. There are four known types of experimental compositions which have been discovered so far on 1999 State Quarters.