Many on this forum (including me) have used, and been very happy with using Plexus in cleaning their bikes. While at the local BCF I noticed an Australian product called Vuplex that gave almost exactly the same blurb on it, as to what Plexus says. The cost there was $19.95, but a quick search shows that Whitworths Marine sells it for only $15.95.
Also, a quick Google search indicated that people who have used it were very happy with it, and seemed to think the results were similar to what Plexus produces.
When I run out of Plexus I am going to give it a go, but I guess that the point of this thread was to see whether anyone here had used it and what their opinion of it was, and also to put it out there that there may be an Australian product that is comparable to Plexus in results, but also cheaper.