I'll provide a few answers of my own below; please chime in with additional ones (or objections to mine, or the way I've worded/formatted/named the Thirsty, or whatever) in the comments.
- Textbooks. If I've named specific chapters that you should read in preparation for particular classes, and/or keep writing things like "see Jones for more on approaches to hamster-fur felting" in assignments, YES, YOU NEED TO BUY THE TEXTBOOK! (sorry; can you tell I've answered a few emails on this subject lately?)
- Time -- time to study, time to eat right and exercise and sleep and generally consolidate/reflect on your learning. Maybe even time to have a life while you're preparing for life. Time is, unfortunately, an expensive commodity, and I can't really recommend taking out student loans in the current economy. So maybe this is one you pay for with scheduling/lifestyle decisions: attend the local CC and/or live at home if necessary, start out with a 6-year rather than a 4-year plan, whatever it takes.
- Tech devices appropriate to the job at hand. To complete the work in my writing (and research and reading)-intensive classes, you do need a working computer (or maybe a really good tablet) with a decent-sized screen and internet connectivity and reasonably up-to-date (but not necessarily cutting-edge) software (and/or you need to take a bit of time to identify and download free programs that play well with the more expensive standard ones, e.g. Open Office). Most 5-10-year old lap- or desktops, or a cheap new netbook, will do just fine. You don't need a smartphone with a data plan (and if you try to read scholarly articles on that little screen, you're going to make life much, much more difficult for yourself).
- An automatic data back-up plan. Actually, you can get this, too, for free, though you'll have limited storage space. But for the cost of one or two coffee drinks a month, you can back up all of your important digital belongings using any of half-a-dozen reliable, set-it-and-forget-it (but do check up on it now and then) cloud backup systems that work very, very well. You can also access your files from anywhere, even that %#@! smartphone.