#1 Try to get your list of books you need, as soon as possible. This gives you the opportunity to look for the books cheap or second-hand. Sometimes you can even get your books as an E-book. I know this is not an option for me, but maybe it is for you.
#2 I also LOOOVE stationary, but if there is one thing you don’t need to invest in.. It would be highlighters. Yes, there are an enormously big amount of different kinds of them. They also can be super expensive.. For a highlighter… Just go for the white brand and invest other stationary items that are worth the price.