I order shellac flakes from woodworkers supply, and generally have
been pleased with their product.  I say generally, because the flakes
usually keep for years.  The last batch did not; it had polymerized and
was useless.  They also have Super Blonde and Garnet flakes.  I prefer
the super blonde for finishes.

  http://woodworker.com/jemosers-seedlac-mssu-848-817.asp 

Mark Ritzenhein