From 1932 to 1964 the U.S. Mint had offered Proof Silver Quarters for collectors to purchase. However, as the price of silver increased, the Mint decided to produce Clad Proof Quarters from 1968 and going forward. In 1992, the U.S. Mint reintroduced Proof Washington Silver Quarters to its line of products alongside Clad Proof Quarters.
The 1997-S Proof Silver Quarter is fairly common and sells at a slight premium above the price of spot silver. Only in PR70 Deep Cameo condition does it bring a significantly higher price but it's still affordable that just about any collector can buy one inexpensively.