^^^ do not take this advice. Interview prep does not give you answers to interview questions. It gives you the tools to answer questions in your own words with your own answers and how to do it confidently and appropriately. Much of it may seem like common sense but it will certainly reinforce good interviewing techniques you may already have.
If you are about to interview for the last job in your professional life that is worth millions of dollars, I'd say a few hundred bucks is a small investment if for nothing more than piece of mind and a confidence boost. If for some reason you don't get an offer do you really want to be at home thinking you left something to chance.
I am in no way connected to any interview prep course but I know emerald coast used to offer you your money back if you didn't get the job. No risk there!