SergeModular

For those in Australia, or how don't mind ordering from Australia:

Plug Banana Stack Type Green
http://www.altronics.com.au/index.asp?area=item&id=P9280
Plug Banana Stack Type Red
http://www.altronics.com.au/index.asp?area=item&id=P9281
Plug Banana Stack Type Black
http://www.altronics.com.au/index.asp?area=item&id=P9282
Plug Banana Stack Type Yellow
http://www.altronics.com.au/index.asp?area=item&id=P9283
Plug Banana Stack Type White
http://www.altronics.com.au/index.asp?area=item&id=P9284

Assorted bananas, including stackables.
http://www.rockby.com.au/searchres.cfm?searchkey=banana+plug