The following information refers to purchasing both Volume 1 (Basic Tools) and Volume 2 (Basic Applications) of this work, both published by Cambridge University Press. Volume 1 has been published in June 2001 and Volume 2 will be published in May 2004.
You may purchase this volume directly from the publisher (e.g., search for Goldreich from the US webpage of CUP). Alternatively, you may place an order with any big bookseller (like Amazon), but beware that past experience indicates that it may take these guys ages to figure out they actually have stock (and in the meantime they will continue to tell customers the book isn't published yet (which is not ture...)).
There is a "second edition" of Volume 1. Its text is identical to the 1st edition, but it is "paper cover" and thus cheaper than the 1st edition (which is no longer available from the publisher, who has sld all copies it had). Currently, there is no "second edition" of Volume 2. Such an edition (similar to the one of Volume 1) may appear only after the publisher sells all copies it holds. My guess is that this may take a few years. For reasons I don't understand, sales of Volume 2 are legging behind the sales of Volume 2, although in my opinion Volume 2 is more valuable.
[This text is reproduced from the preface to Volume 2]
Writing the first volume was fun. In comparison to the current volume, the definitions, constructions and proofs in the first volume are relatively simple and easy to write. Furthermore, in most cases, the presentation could safely follow existing texts. Consequently, the writing effort was confined to re-organizing the material, revising existing texts, and augmenting them by additional explanations and motivations.
Things were quite different with respect to the current volume. Even the simplest notions defined in the current volume are more complex than most notions treated in the first volume (e.g., contrast secure encryption with one-way functions or secure protocols with zero-knowledge proofs). Consequently, the definitions are more complex, and many of the constructions and proofs are more complex. Furthermore, in most cases, the presentation could not follow existing texts. Indeed, most effort had to be (and was) devoted to the actual design of constructions and proofs, which were only inspired by existing texts.
It seems that the fact that writing this volume required so much effort implies that this volume may be very valuable: Even experts may be happy to be spared the hardship of trying to understand this material based on the original research manuscripts.