Paper
Many spells contain a written component. Something often needs to be written down, if only to be burned. And so, paper is required.
Classical grimoires often suggest that one uses parchment or vellum, especially when creating a talisman. The advantage of these is durability, although they might be difficult to acquire nowadays. Hoodoo often suggests the use of brown paper. Use cut up paper bags or butcher's paper. The advantage of this is the low cost, easy availability and color--brown is the color of justice. This paper thus enhances any spell that demands that justice be done.
It is also very easy to create your own paper with minimal skill and artistic talent. Children's craft kits contain basic paper-making supplies. A spell rarely requires more than a sheet of paper. The advantage of making your own paper is that you can imbue it with desired herbs and fragrance.