1976-S Silver Bicentennial Quarter in Proof Set: This coin is rare due to its silver content and proof condition, potentially fetching nearly $10 million at auction.
No S Proof Bicentennial Quarter: A bicentennial quarter without the "S" mint mark in proof condition can be worth over $150,000 due to its scarcity.
Double Die Obverse Variety: Bicentennial quarters with noticeable doubling on the obverse side, particularly on the date and lettering, can command prices exceeding $150,000 among collectors.
Full Step Example: Quarters with full steps on the drum's staircases on the reverse side are rare and valuable, potentially reaching values over $150,000.
1976-D Bicentennial Quarter with Mint Error: Quarters from Denver with striking errors, such as off-center strikes or missing clad layers, can be worth over $150,000 depending on the severity of the error and collector demand.