If anyone in Brisbane is interested in battery power for out in the field, I picked a Ritar 45Ah AGM deep cycle battery up yesterday from Springers Low Voltage in Lawnton for $159. If you need bigger ones they have those too. There is 20% discount on these this month.
http://www.springers.com.au/product.asp?SKU=198
I am not affiliated with them - but have been looking for batteries for a while, and these are a good deal.
Cheers
Adam