I’ve already linked to this site before, but I have to mention it again because I’ve gotten some very good use out of it in just a few weeks. It’s a real go-to.
You get free information from several solid commentary recommendation books (Carson, Derek Thomas, Glynn, Longman, Rosscup). These are the sources you should be checking—and mostly trusting!—anyway. And the information is collected in a very convenient and attractive format. You can browse by series and by Bible book. You can look up prices. Very nice.
Put this site in your bookmarks toolbar!