Malaysian Bookstores usually have a decent collection of books . Unfortunately, most of them located in Kuala Lumpur.
The non KL residents then only have the option to purchase books from online retailers like MPH, Times, and Kinokuniya. They all offer free delivery with purchases over RM 200 for the first two, and RM 300 for Kinokuniya.
Largest bookshops in KL:
Borders, an American chain at Times Square. It has one of the widest selection of English-language books and magazines in the country. Promoting that it has more than 250,000 books in the store, the one thing that differentiate Borders from other bookshops in KL is that it doesn't wrap its books in plastic. So you can browse through before buying them. It is under management from Berjaya Books Sdn Bhd.
Kinokuniya, a Japanese chain, at KLCC. Despite being a Japanese store, it has more English books than Japanese. Also features a large selection of architectural and design titles. An annex, located in the nearby Isetan department store, specializes in Japanese comic books. They also have a good little cafe selling snacks and coffee on a mezzanine above the store.
MPH, a Malaysian chain, has the most branches in KL. It sells books in English, Malay and Chinese and, in some stores, also has CDs and DVDs. One of their most visited branch is their megastore in the MidValley Mall. It has a cozy cafe where you can sit, enjoy a latte and read what you just bought.
Times, a chain of retail outlets throughout Singapore, Indonesia, Macau and, of course, Malaysia. They have outlets in Pavilion, Bangsar Shopping Centre, Hartamas Shopping Centre, CapSquare, and Sunway.
For used books, check Pay Less Books and BookXcess. The former has outlets all over the metro area, two of the largest being located at Ampang Point mall in Ampang, and at the AMCorp Plaza mall in PJ. The latter is located in AmCorp Mall and has a very user friendly website.