9600GT/ ATI 4670 are slight faster than 3850. Howover, both using less power.
According to pricespy.com.au, they are around AU$70 - 90, so for 3850, I would say AU$60
It's a tad old, you'd honestly be far better off getting a similarly performing current-generation card, it'll use less power and run cooler not to mention it has all kinds of features, toys and whatever these newer generation cards have...
Yeah I'd also recommend something newer. maybe a 5670. When i had a 3870 it had 320 stream processors, which is not a lot for ati cards today... my midrange 5770 has 800, my 4850 also had 800.