Plan B, though not quite free, is to stop by your local dollar store - they quite often sell cheap multi-packs of the little pawns used in games like Parcheesi; and these make great pieces to represent generic mooks or 4e-style minions. Or, buying a cheapo chess set will give you 32 pieces - with some variety to them as well.
Plan C, close to free but not quite as elegant-looking, is to take some sticks of scrap wood and cut them up into little bits of varying sizes then paint them a few different colours.
Lanefan