Of the two reprint volumes (Greek and German Philosophers) that Oxford has published of its Past Masters series, I think all of the individual essays (except the one on Plato) are reprinted currently in its 'Very Short Introduction to...' series. So these volumes are a good deal because i think the 'Very Short Introduction' series are 10 bucks each. As well as being very clear and concise introductions by world renowned scholars.
Oxford University Press has done a great public service by publishing its "Past Masters" series. Each title in the series is an incisive account of a particular thinker published in a portable and inexpensive format. I only wish all of the titles in the series had been available to me during my undergraduate years! The three titles included in this one volume on Socrates, Plato, and Aristotle are welcome additions to the Past Masters series. All three essays are written with clarity and grace, and are worth the attention of novice and specialist alike.