Many of dar al-ilmiyah and dar al-fikr books are available at archive.org, just search for books, lannguage arabic, you'll get a huge list.
As an aside, there is a lot of criticism against Dar al Kutub ilmiyyah, perhaps more than they deserve, the following links (non sunni) do have some useful information though: http://attahawi.com/2009/05/12/unde...ning-conversation-with-shaykh-husain-kadodia/ http://islamclass.wordpress.com/2012/04/20/the-best-editions-of-arabic-books/ (There is also a website that I found recently (though have not yet used) called Jamalon where a lot of Dar al Kutub's books seem available to purchase with comparably low delivery costs.)