After ringing people from Exmouth to Busselton I had no luck in finding
anyone actually growing tree onions, but my local nurseryman had a catalogue
from Tesselaar Bulbs and Flowers, 357 Monbulk Rd, Silvan Vic 3795: 20 bulbs
for $8.50. They don't seem to have a restriction on sending the material to
WA, unlike other mail-order companies I've tried.