I'm addicted to books. Especially used boos with a very good pricing. My favourite used book stores will definitely be PAYLESS BOOKSHOP. And the trick is to go for their REAL warehouse sale. It's because it's done at their warehouse (without air condition ...).
The catch is tons of books costing between RM1 and RM2. And with a budget of RM 200 ..you can comeback with 100 books plus a big smile.