I'm trying to make a decorative match cube
Color your own!?!? I checked they make yellow and white. that is because of the chemicals.
The 'Black Strike' on a matchbox/matchbook is nothing more than very fine sandpaper or carborundum (sp?). It creates friction for the match head to reach ignition and set the next flammable material ablaze.
I would first try the supermarket. If that fails I would then try Google.