Except evidence and history proves otherwise, Nvidia had the 260/280 at roughly £300/£400 on release? ATi came out with cards, that actually competed they COULD have simply released the 4870 at £350 and the 4850 at £200 and no one would have batted an eyelid based on the fact that the 4870 was faster than the 260 and so could be priced higher.
Yet ATi, knowing exactly where they COULD price their products launched them at roughly £180/£130 price points severly undercutting Nvidia with no competition.
They could bring out the 5870 at £300, and sell 500k of them making £100 profit per card thats £5million total profit.
Or they can sell it at £180 and only make £50 profit, but sell 10million of them, thats £500,000,000.
Remember if they increase the price from £180 to £300 the don't make an extra £120 profit, they get the same percentage, their price goes up but the card makers make a chunk of that extra profit for themselves.
Price lower, sell 100 times as many, have 100 times as many produced in total cheaper to make as they can get better deals with the manufacturers.
Theres no reason for ATi to go expensive, nor will they increase profits by doing so, they'll DECREASE profits by doing so.