I just found the first volume of Handbook of Logic in Computer Science in a library, but unfortunately I won't be able to use it here. It seems like a great resource, but it's insanely expensive to buy - is it worth it? Do you know any good alternatives?
The series is a wonderful resource, but I wouldn't recommend buying it when it is available in the library, unless you knew you were going to use it for many years to come. (I have too many expensive books on my shelf that are lovely to look at, but not used much.) Many articles and tutorials with comparable contents are available on the web. These are probably a better alternative for the moment, in my opinion.
Some years back, the rumour grapevine told me that more volumes of the series were planned, but the series was stopped at the fourth because preprints of nearly all the chapters were made informally available by the authors from their websites.
The series is very classy, and it's a shame that it didn't continue. The rumour, if true, would support both sides of the debate over preprint culture: either it shows just how successful the preprint practice has been at making valuable content widely available at no cost, particularly to graduate students who might otherwise not afford more than limited access to these texts. Or it has undermined the effort of top-notch publishers like OUP to make first-rate, well-edited and well-typeset research publications available.
Nobody needs these volumes, as supercooldave says. But if you have the money, and value the physical product, why not? It supports the best part of what looks to be a dying industry, and you will like holding it each time you take it off your bookshelf.