We've stayed at Starline Alpaca Farm at Broke in the Hunter Valley a few times. Only 2 - 2.5 hours out of Sydney, nice dark skies (well for a Sydneysider!) where you can visually see the dark lanes along the Milky Way. It does get cold, but hey.
They have a number of cottages, we always get 'Lucy's Cottage' to get away from the main row where families with kids stay.
http://www.starlinealpacas.com.au/
Cheers,
Jason.