Great tips from a College RA!
buy a mesh shower caddy rather then a plastic one (easier to clean and limits mold!)
buy a tower fan rather then a little woozo type fan (cools the whole room rather then just one part and easier to store then a box fan)
buy a bath robe rather then tons of towels (best for communal bathrooms and walking back and forth from bathroom to rooms)
buy a mattress topper rather then NOT buying one (dorm beds are like bags of rocks)
buy totes (blue IKEA bags are great) rather then compression storage bags (best for moving out and easy access to stuff)
buy a mini fridge* with a freezer section rather then one that is all refrigerator (needed for students who like ice cream and chicken nuggets!)
buy an air fryer* rather then a toaster (most air fryers come with these plus this limits trips to the dorm kitchens and amount of appliances!)
buy a larger trash can rather then a tiny desk one (helps limit how many times a week you take trash out!)
buy/rent books from chegg or amazon rather then the school book store (SAVES SO MUCH MONEY)
buy folding/butterfly chairs rather then a futon (just as comfy but can be stored away!)
buy a rolling laundry hamper rather then a bag ( so much easier then you would think to take down stairs and elevators, plus it takes longer to fill it up!)
*Disclaimer: please check school requirements and rules!