With the prices of admission to all the major theme parks being around $80-$90 per adult per day, it is well worth spending a few dollars on a couple of good guide books.
There are a couple of guide books that are written solely about Universal Studios in Orlando and many other books on Orlando that have chapters dedicated to Universal Studios. Therefore you should probably choose a book based upon what else you plan to do in Florida.
Note that most guide books are re-published annually so you can often pick up a bargain if you don't mind last year's edition. You won't get the very latest information but you could save yourself quite a bit of money.
Also look out for special deals on most Internet book sites where you can often buy two related books at a special discounted price.
The 2018 edition of The Unofficial Guide to Universal Orlando by Seth Kubersky was published by Universal Guides on December 12, 2017. Seth Kuberky is no stranger to Universal, having once worked there and has written other books on the subject including earlier editions of Universal Orlando: The Ultimate Guide to the Ultimate Theme Park Adventure.
A companion to the long running The Unofficial Guide to Walt Disney World edited by Bob Sehlinger with Seth Kubersky, the 9th edition of Beyond Disney: the Unofficial Guide to Universal Orlando, SeaWorld & the Best of Central Florida was re-published on November 10, 2015 and is an insiders guide to Central Florida’s non-Disney attractions.
Universal Orlando: The Ultimate Guide to the Ultimate Theme Park Adventure 2015 was the first book solely dedicated to the Universal Studios theme park resort in Florida, rather than being tacked on to one of the many guide books about the Walt Disney World Resort or Orlando.