I will actually answer your question here.
Here are the best resources I found after extensive research on this very topic 6 months ago when I began my prep process (I passed the Oct exam):
-EE's Guide to Passing the Power PE (my favorite resource, however there are a couple of errors, be sure to check the eratta on the website and make sure you correct the delta-wye conversion (or maybe it was the wye-delta, can't remember) somewhere early in the book, was missing negative signs in the angles. Amazon was the only place I could find it 4 months ago, but maybe will have more luck earlier in the exam prep process.
-GA Tech binder. I know it's from a prep class and if you can take a prep class, do so. This one was good, I"m sure others are good too. This and EE's Guide were my two go-to resources.
-Power System Analysis by Granger (didn't use a ton, but was helpful for clarifying topics and at times had better equations/graphs). Just get an older used copy on Amazon.
-NEC: obviously need to get this. Get tabs for it too. You'll need the 2017 so finding used copies may be a problem.
-NESC: some say it is not needed, others say for sure get it if there is any way you can afford it. I'm of the later group. If there are two question on the exam and this is a guaranteed two easy questions, then I say it's worth it. You can sell it later too to recoup much of the cost. Not sure the best place for this, I bought straight from the source.
-Spin Up practice exams AND Complex Imaginary practice exams. Two different books with two flavors of questions. I would say get both if you can. If only one, it seems the Complex Imaginary is more popular but that's just my feel of things. It may be hard to find copies that aren't already marked up, but give it a shot. I ended up finding the Spin Up on Amazon and had to buy the CI from the company itself.
-Machines by Wildi is good (latest edition), though it wasn't much help on the exam (was crucial for a single question though). Maybe I didn't look through it enough, but it's a well put together book with lots of practical insight into the field. I plan to read this book for my own learning after the exam, it's that good.
-FE reference manual: didn't use it on the exam but if there are econ questions, this one may help. I'm sure others have a better reference for the econ questions.
-I would maybe have a power electronics book handy too.
Look for used sets of books on ebay. I've seen a few folks that have most if not all of the resources in a package (minus maybe the GA tech binder and FE ref manual)
My best advice is to compile notes and references into a reference sheet. That way on the exam you can look at that first to know where topics are in your various resources, instead of having 50 tabs in your books. Also, make sure you know a small handful of resources front to back pretty much. Take as many extra books "just in case" as you'd like, you never know. Don't rely on these extra books, but it's good to have them there. I know I was glad I had them and did use a couple. Don't worry about taking a suitcase in if you need to. Let people make fun of you for it, now is not the time to worry about what people think.
Good luck!
