Hi jackyngew
Your question is the same one asked by developers such as AV Jennings, Mirvac, Australand, Austland, and so on and so forth. Tracts of land of that magnitude, in large part, has often been already land banked by development groups such as those I've mentioned, for future development. Other tracts of land that are of that size if not already landbanked, are not zoned appropriately or are rural/farm land and can't be developed in the manner I think you're seeking.
There are, however, a number of large tracts of land that have undergone subdivision or had development started in the hands of receivers/agents, that may suit your purposes, if you have someone on board who can do the feasibilities and demonstrate highest and best use of the land you're considering. That might be a less frustrating and more available source of projects for your group. I know of a few people who may be able to assist on that front if your group has more specific parameters etc.
IT all depends on their level of investment, their apetite for risk and expected returns etc.
Matt.
