I heart the paper products at Paperlera Palermo. This store should also be under your MUST VISIT list for Buenos Aires. I got some very cool notecards and a journal. The notecards are already running out and I wish I had got more. Their website is in Spanish, but you can use this tool to translate.
I live in Buenos Aires, and I LOVE Papelera Palermo!!!!!
Always find something to buy 🙂