Grandmoon, just a suggestion but start with the main local banks and ask the Manager to put you in contact with their public relations people in their head office.
If you are in a regional area there is a bank called Rabobank who are very community minded.
The other ones to try are local philanthropists like Dick Smith, Lachlan Murdoch and James Packer, I believe that all have community related departments and are very approachable.
Another alternative which worked here for a community project which needed to be built was to approach several of the local builders and large hardware stores and together they all pitched in.
Of course it all depends to a large extent on the charity.
