The 1908-D Barber Quarter is a great collectible coin because it is plentiful and it often comes nice. Most examples come well struck and many of the top coins come with remarkably colorful toning. In Mint State, the most common grades are MS63 and MS64. Gems can be found without too much difficulty, but above MS66, this date is a true condition-rarity. The best example is the NGC MS68 from the Eliasberg and Gardner collections.
Stack's/Bowers 2/2015:1560, $7,637.50