My feeling is once the blade has been mounted in the saw, it is a used blade. I do not use used blades! I buy blades by the gross. That averages out to about $0.23 a blade. That's 23 cents! It's not worth it to me to put a used blade in, and then have to change it because it's not sharp enough. So, if it's used, it gets tossed.
I use plastic tubes for blade storage. I have a wooden rack with holes drilled in it to hold the tubes. I used a lablel maker to identify what's inside.
As you can see by the picture, the tube on the table tells me what blade is mounted in the saw.
I buy my tubes at http://www.sloanswoodshop.com