A Hint for Cleaning Oil Pastels

I love the look of oil pastels, but haven't done much with them this year because our oil pastels are in such bad shape.  My budgets are tiny and I order a few new sets each year, but there are never enough to go around.  As time goes by the new ones find there way into the big box with the old ones and before long, the new ones look just as bad as the old ones. Nothing to me is as frustrating as watching a kid encounter that unexpected muddy streak in the peach or the pink. It's so demoralizing.  

Last night I discovered that olive oil works pretty well to restore old craypas by melting away the grime.  To start I set out a splash of olive oil in a little bowl or cup.  Each craypas got their tip dunked into the oil and then wiped off on a paper towel.  I tackled all the warm colors first, then went for the cool colors.  Not as easy as the chalk and rice trick, but effective. 
Next step, teach the kids how to do this task.
Okay so, I have my pastels sorted by color into a muffin tin right now, but am looking for a better system.  The original boxes are long gone.  So tell me.  How do you store your oil pastels?