Five star Flex Binders! These are so awesome. I think I bought mine 2 or 3 years ago and it is still going strong! They fit nicely into my laptop bag and make traveling to school pretty light.
Colored Pens! The brand doesn't really matter but I purchased these last year and they were either FREE or just $.25!
Poly Folders! I still purchase the 2 pocket paper folders when they are on the $.01 sale but I usually donate those to family or our supply drive at work. I love the poly folders that have holes punched in them. They give me extra space in my Five Star Flex binder.
I am sure I could sit here all day long and post about of all of the fun things I NEED to have for back to school but I will leave you some time to check out all of the other things that have been posted.