Paul,
I went to Bunnings, and the extremely helpful bloke behind the trade counter told me of a few types of glue that were similar in composition, but very different in price. The first tube I used for my floor and some of the walls was Selleys Adhesive + Sealant, the second (I brought a few tubes of this stuff) is Bostik Gold, and the third was Sikaflex (very expensive), all are a flexible adhesive + sealant. I ended up getting the Selleys for $10.65 a tube, and the Bostik for $8.25 a tube, and from memory, the Sikaflex was $25 a tube.
I couldn't live without my Triton workbench, it's so versatile.
Good luck with the rest of your build. Will hopefully meet you sometime during Easter 2007 (if the minister of home finance still says yes).
Cheers
Adam.