Felix to Oscar (Dencan Books) next door, The Book Exchange is an organized and quaint little used book store.
It's collection may be small, but the quality is definitely there, offering gently used books, rare books (mostly hardcover) and even a few remainder and new books in various titles, both popular and unexpected.
It also holds good hours, open late (9pm) Tuesday to Friday, catering to those who can't get to these little shops during the day.