thoughts without purpose

I’m in the process of getting all my passwords and usernames for online things all together so that if I ever forget any of them, I can just look at the list and log in.  At the Container Store, you can buy a small notebook that will “manage” all your online account passwords and usernames and such.  It was $9 for a book the size of an address book that really offers nothing but special pages for you to write these down on.  Why would someone need to spend that much when it is so easy to just write them down on a Post it or in a much less expensive notebook?