Dan, a popular entry-point choice appears to be the little Ozito router sold a Bunnings for about A$50. Check out the numerous threads at Woodworkforums CNC Section and in particular this thread. If you have a bit more cash to throw around, it may be better to go straight with a quality die grinder or even a spindle as discussed on this thread. A search on woodworkforum will throw up other discussions on routers/die grinders/spindles suitable for CNC applications.
I have haven't begun building my first CNC machine yet, but have the HobbyCNC 3 axis kit on had (luckily I bought it before the A$ dived) when I get around to it.. too many other projects on the hop at the moment.
Keep us posted (with pictures) on the progress of your build.