Writing in the 2007 edition of the invaluable reference Standing Liberty Quarters, J. H. Cline describes the 1920-S thus:

The 1920-S is a very rare item in true Full Head. It should be valued many times over Red Book price. I rate it second or third in value for the entire series. It is always a weak strike in both obverse and reverse and is very much underrated.

The example to the left was sold by Stack's Bowers Galleries in the November 2010 Baltimore Auction, where it realized $46,000.