In sydney, for small amounts, Clark rubber and Foam Booth have the right foam, but rather expensive. I was looking at the same problem myself, found a mob called Adfoam who sell the stuff in sheets more or less 2m x 2m and 5cm thick for around $100, which works out cheaper per cubic foot by a substantial amount. I just received some samples from them today(extremely fast delivery) They are at 9 Ford St, Greenacre, phone (02)9742 6900. They also sell 300 litre bags of offcuts for about $15, the ultimate el-cheapo way around packaging.Hope this is of some use.
