So I went and bought
- a cute red binder
- a tab organizing whatever-it's-called thing where you can sort the papers in alphabetical order
- a plastic thingie (apologies for my lack of filing-related vocabulary) where you tuck in the papers so that they stay nice and smooth
- cute sparkly stickers!
Now it's ready to accommodate stacks of new sheet music! (The light makes the binder look a bit pinker than it really is)