My favourite is Elizabeth's as seen in the photo. They have a store in Newtown and Pitt St, they have such a huge variety of books and always at very attractive prices. I recently bought a large, antique book about Cleopatra that was in immaculate condition for $10. I love it!
I can't go past Mr Pickwick's Fine Old Books in Katoomba. The place is an absolute labyrinth and you can easily spend hours searching the shelves. Sappho Books in Glebe is also a good one, as is Bridgepoint Books in Mosman.
I have visited second hand book stores in the Blue Mountains area which have been incredible, and stores in Newtown which have had a disordered, yet wonderful charm, but my personal favourite is a small store in the Epping arcade called Recycled Reading. The reason this store is my favourite is because it is small, local, easily accessible (it's conveniently close to Epping Station) and the owner of the store is so friendly and polite. It really is tiny though, so if you're hoping for a long, intense browse, I would probably do the trip to Newtown or the mountains instead.
Shop 9, Epping Club Walk, 52 Rawson St
Epping, NSW, 2121
Definitely Elizabeth's! I recently spend a whole afternoon there. If you want a bookshop adventure, head to the other end of Newtown and poke into Gould's... it's absolutely massive and has rabbit warrens of books stacked absolutelyu everywhere! You never know what you will find.
Brilliant Kat, very good question :) Newtown comes to mind, yet there is a place at Darling Street in Rozelle - right near Potteround that sounds really good...gees for the life of me I can't think of the name when I need to the most...
Not sure if you're referring to Sydney CBD or greater Sydney area. If you're willing to travel, I highly recommend the Blue Mountains. My favourite places are:
Mr. Pickwick's in Katoomba
Lamdha Books in Wentworth Falls, and
Brown Books in Springwood
I've visited some closer to Sydney but can't remember the names. They were in Newtown.
If you're after a particular author, your list might be reduced easily. For example, if you're after P.G. Wodehouse, I'd recommend Lamdha Books. If you're after Terry Pratchett, I'd recommend Brown Books.