Well, interesting you compare the 285 to the 4870, while the 4890 beats the 280 in most games, and does very well against the 285, and the newer drivers put the 4870x2 very close to the 295, with wins here and there as well.
I think nVidia plays catch up, then charge too much, if we want to look at whos "cheap" or not. nVidia then is "overpriced"
I dont believe ATI is second fiddle, and Ill be surprised if nVidia does have a solution to those "bang for buck" 5970s