I pulled the trigger on the 12V solar fan today. Ended up going for the 5W panel:
http://www.jaycar.com.au/Ecotech/Sol...---5W/p/ZM9091
DC-DC converter:
http://www.jaycar.com.au/Power-Produ...-1-5A/p/AA0372
120mm fan:
http://www.jaycar.com.au/Electromech...e-Fan/p/YX2584
No batteries at this stage but might add them later if necessary.
Wired it all up today and it works!
Just waiting on some grilles to arrive at Masters
https://www.masters.com.au/product/9...?bmUID=l7831Ro
and need to get a 12V fuse holder.