It is possible to buy books printed with word search puzzles, however a more flexible option is for a parent or teacher to create the puzzles themselves with the help a computer and word search puzzle maker software. Simply enter a list of words, and the computer can generate a puzzle in an instant! Doing it this way has the big advantage that you can tailor the puzzle, for example choosing words based on this week's spelling list or around class project, or perhaps turning off some of the more difficult directions when creating puzzles for younger kids.
Creating word searches by hand, whilst possible, takes a lot of time. Also, once you've hidden all the words yourself, you'll probably remember where they are when it comes time to find them again. This is where the internet can help! If you search the internet you can find a number of useful resources which let you enter a list of words to create your own, personal game. I particularly like Word Search Party because it will spell check your words as you enter them, which helps catch those typos before you start hunting for the words! You are able to set the difficulty level to something you (or your intended audience) is happy with, and create a wonderful, personalized word search puzzle.