Sirius Optics (
http://www.sirius-optics.com.au/nikon%20sscope.htm)
and
NVT (
http://www.nvt.com.au/Spotting-Scope...e-Accessories/)
both list the Nikon zooms on their websites, but you could also try BinTel in Sydney (
https://www.bintelshop.com.au/welcome.htm), who list the Nikon spotting scopes if not the eyepieces.
There may be others too - spotting scope buyers are a different mob from the astro crowd!