I am a big non-fan of props in auditions. I want to see that you can create a character just by the use of your voice, face and body. If you can do that, I have no fear of how you will do in costume with props and a set. If you are doing an aria that calls for a book, or a sword, or a flower, either pantomime it, or create a staging that works around it. I know that some people don't mind the use of small hand props in auditions. but I don't think you can go wrong if you learn to be a very effective and convincing auditionee without them.