Books In Print, published by R.R. Bowker, is the primary tool for looking up books in print. You can look up books by title, author or subject, and each record also tells you the publisher, price and ISBN number. The print version of BIP is generally available in libraries and books stores. If you are lucky, you can search the current edition for free through the Web site of a public library or other organization that has an arrangement with R.R. Bowker. There is also a Books in Print CD-ROM and a subscription-based online edition (www.booksinprint.com). I believe the electronic versions all include of Books-Out-Of-Print back to 1979 and one year of advance publication titles. The CD-ROM includes book reviews.
Alternatively, you can use Google Books or search the catalog of an online book store for information or to buy the book (See "Book stores"). If that doesn't work, you can search OCLC's WorldCat and/or the Library of Congress' Online Catalog to find books and bibliographic information - then call the publisher to see if it's for sale and for how much.
Legal Materials: As you might expect, there is a legal version of Books in Print called Law Books & Serials in Print, which is also published by R.R. Bowker. In addition, InfoSources Publishing produces Legal Looseleafs in Print, as well as Legal Newsletters in Print and the Directory of Law-Related CD-ROMs. These books are available in hard copy, or you can search them on InfoSources' LawTRIO database. See also "Legal Treatises."
Used Books: To buy used books, see "Used Books."