The 1876-CC Twenty Cent Piece is a true rarity with fewer than 20 pieces known to exist. Mint reports indicate a total mintage of 10,000 pieces before production was halted, and subsequently all of the mintage was to be melted. A few pieces, however, did escape destruction when the issue was allegedly melted around March 1877. Some of the pieces were presumably set aside for the annual assay commission, however it is also likely that a few pieces were saved by Mint employees as souvenirs.
Needless to say the issue is extremely rare, and few pieces have come to the market in recent years. A reasonable price is hard to determine and truly depends on market conditions and demand at the time a piece comes up for auction. An MS-66 sold for $460,000 in 2009, establishing an auction price for the issue. It must be noted that all pieces that are still in existence are in uncirculated condition, confirming the theory of how these escaped the melting pot.