8800GT(S), 3870 (I recon the 3850 would do too), 9600GT and the 9600GX2 would be the only options to consider. (or ofcourse lower end models if thats what you want.)
I use a 3870 myself, and I'm very pleased with it. power consumption might be an issue tough (with all of those cards) but the idle power consumption of the 3850/3870 is much lower than that of the 8800's, wich is actually a big plus imo.
Sorry campo it's in US. You have to specify even though it says your in Australia in your profile. The following are in AU prices and I found them by using staticice.com.au
You can get a 3870 for around 240 AU plus shipping.
9600 GT is going for around 195 plus shipping. The brand is XpertVision. Not the best though. But my 7600 GT is from them and I have had no problems with it.
8800 GT 512 MB is going for around 240 plus shipping. Again the brands aren't that great.
8800 GTS 512 MB is going for 330. You guessed it, brand isn't the best. And of course plus shipping.
I would go for the 9600. Mainly because they are cheap now and if you SLI them (run two nVidia graphics cards) when they become even cheaper you will get a fair bit of performance boost. A bit below 100 % performance boost I think. Which is pretty good.