You can now get good, solid commentaries of both the Old and New Testaments via Google Books. This includes such commentary sets as The New International Commentary on the Old Testament (NICOT), The New International Commentary on the New Testament (NICNT), The New American Commentary (NAC), and a few others. This allows one to access scholarly and academic works of commentary on the Scriptures, but without spending hundreds (or thousands) of dollars. Well, I should say that not every single page of every commentary is available. But good portions of them are available through Google Books.

For the Old Testament, click here. For the New Testament, click here.