Why would you keep more than a couple hundred? Cure disease is a mostly useless potion. Unless you are eating far more than you should or are particularly low in hit points, any disease will wear off before you take significant damage. Sure five sand cookies killed me pretty quick with indigestion but I don't eat them anymore. At least if you sell them to npcs you can imagine them doing good on other levels.
This is a problem with all crafting, though, as in most games. The sheer volume of stuff created is never realistic to the demand from the user base.