I was looking for some cheaper ones and didn't find much recently online so this is just a
placeholder if anyone searches.

In Adelaide

black star droppers( not galvanised ) 1800mm ,
Bunning/Stratco $14-16 each

look at ag and steel suppliers
Found a couple nearer my expected price, of course FREE would be the best price :-)

Landmark, corner of pt wakefield and montague road $6.35 ea incl gst in pack of 10

Paramount browns, actually the steel place next to them, forget exactly but $6.xx , around
same as Landmark.

Maybe you could get cheaper, but are they less than 1 km away? :-)