Pegasus Books is at 5560 College Avenue in Rockridge, and is part of a small chain, with two other stores in Berkeley. The one in Rockridge has been there since 1969, and used to be called Pendragon Books (hence the pendragon on the sign.) They sell used books and some new books. Every year they have a enormous calendar sale which seems to start after the 1st of the year and last until June and the calendars get progressively cheaper (as they should). The bookstore is very browser-friendly. They accept used books for sale but they must be in good condition.
Pegasus has a great "new arrivals" used bookcase that can take up a good portion of time if you're waiting to eat or have just come from eating somewhere in Rockridge or if you just like to browse and buy.
Their magazine section is pretty literature/arts focused, they also carry a fair amount of zines.
Pegasus Books was the recipient of the East Bay Express Best Bookstore Readers' Poll Award in 2014.