Charcoal and Pastel Drawing Storage I need to store a lot of charcoal and pastel drawings as I've recently gotten back into drawing.

I can't afford a proper solution such as a flat file at the moment.

I'm worried about stacking the drawings on top of each that can lead to possible damage on the drawings. I also don't want to leave them exposed to dust. 

Is there a cheap solution that I can place between and on top of the drawings for the moment until I can afford a better solution?
I would lean toward using acid-free tissue paper.  It comes in all sizes and you can cut out sheets large enough to separate your drawings.  I think this is similar to what my sisters use. 

Of course one of the things that could help preserve them is spray a fixative on them, to help keep them from smudging.

Last if you need a physical container, there are plenty of different shaped plastic boxes, many big box stores have different options for $5-10 a piece.  Combined with the acid-free tissue paper you can store quite a few drawings in a safe location away from the elements, dust etc.