This is not the way to put it , who wants to spend 500$ on a graphic card will look for best perf. and doesn't really care about price/perf. ratio.
The battle is where ATI 4850 and 4830 are and for Nvidia 8800gt/9800gt and 9800GTX/GTX+ and of course lower end wich might be even bigger in profits than this.
Comparing 4850 with 9800GTX's the GTX is about equal in perf. overall with the ati card but the ati card is a bit cheaper and is more cheaper to produce by integrators than Nvidia product and that's why some of them build ati cards now.
Then , the new 4830 is again at about the same price in most cases but you can get it cheaper than 9800GT , it's faster than the Nvidia card and offers better price/perf..
Now if we go up a little in an enthusiast segment wich might not be so profitable but still important for them (ati,nvidia) is the 4870 against gtx260 , it's cheaper and at stock speeds equal overall , of course if you overclock the Nvidia card is better but for people who stay stock again ATI gives better price/perf.
This is applied for all times , whenever Nvidia launched a product in some segments ATI eighter launch better ones or reduced price , best example now is the 4870x2 wich can go as low as 399$ on newegg and GTX295 is 509$ , they could've stayed with the same price but they acted imediatly with price cuts.
Those graphs made by wizzard where valid at the time of the review for a few graphics card in that table but by now prices are reduced times changed , they change every month maybe even faster.
You know 4870 is cheaper than gtx260 , you know 4850 is cheaper than 9800GTX/gtx+ , you know 4830 is cheaper than 9800GT , what is the conclusion ? want to make a VS now and make the Nvidia cards faster ? you know perf. varies from game to game and overall they are almost the same in perf..
I'm glad Nvidia is doing so bad , they got cocky and treated poorly the costumers , high prices when they where at the top and ATI couldn't do anything , total ignorance to people's problems with the hardware faults of G80 GPU (that is memory leak that is still not solved even today) , renaming the same product again and again and again.