Try this place:  http://www.leevalley.com/home/main.asp

They have a number of types of shellac, also felt disks and small
sheets.  Your local K-mart type store sells hard felt sheets and
circles (discs) in assorted diameters, with sticky tape on one side
for furniture feet, about 1/4-inch thick.  They are also good to use
as polishing discs with metal polish and a Dremel type tool.  They
are cheaper than the ones sold for it.

You can also try using felt polishing bobs or wheels; you will have
to cut them from the wheels but they do come in assorted hardness.

And then there is always the standby source for all things:
  http://www.mcmaster.com/index.asp

But I understand they are no longer shipping to Canada.

Glen R. Perye Jr.