When you want to ~levitate~ your grades.$13.81, Rakete Berlin on Etsy.
Just add an undetectable extension charm, and you can carry as many books as Hermione.$34.95, WB Shop.
You read this in Alan Rickman's voice, didn't you?$12, Alohomora Design.
Hopefully you'll keep it more accurate than most of Professor Trelawney's prophecies.$40, Ruskerville on Etsy.
Also available in Gryffindor, Hufflepuff, and Slytherin.
You'll have a more organized library of texbooks than Madam Pince.$10 for 15 bookplates, Deeply Dapper.
Accio treacle tarts.$19, Midnight House Elves.
Because, as Ron says, "That's what Hermione does."$15, Alohomora Design on Etsy.
It's like fanfiction for your locker.$15, Logophiles Anonymous on Etsy.