I've gotten some very good books off Metropolis; including several Targets, a few Phantom Lady appearances, and two of the three complete issues of Peter Wheat News I have. I would warn to be careful if grabbing something low grade from them, though- they sometimes but not always mention damage that brings down the grade.
That's just a heads up, though: like I said, I've bought a lot of books from them, including quite a few three-figure ones, and have been quite happy. Just be ready on some of them if the price is low.