So for me I see 2 sides of this.
I tend to agree it's a bit outrageous, but on the other hand I think the market they are trying to appeal to is not an Australian market. Rather they might be trying to appeal to a foreign collector where the depreciating $AUD is making these cars cheaper in their eyes. A collector in Japan might just pay the asking price for an original R100 coupe.
These are very rare now, especially because so many were abused and turned into fully hectic drag cars, how many original ones are left?
The Mazda Cosmo is probably also pulling values up since they have hit the $250,000 USD mark recently and others may be looking for other early rotary's are pinnacle cars and more so as an investment than anything else.
You have to remember about 10 years ago when a Toyota 2000GT came onto the market in Australia priced at $350,000 AUD people were saying it was ridiculous and over-priced also. Time has proved they were wrong.
Will it be the same for these? Hard to tell.. you can still get a lot of cool classic cars around the $30,000 range. I've always liked the early rotary coupe's - especially when they were cheap. Funny enough I've always hated the way most were modified though.
Either way it does make S30z's look cheap right now...